As filed with the Securities and Exchange Commission on September 6, 2001.


                                                Registration No. 333-68278

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                      SECURITIES AND EXCHANGE COMMISSION
                             Washington, DC 20549

                                --------------

                            Amendment No. 1 to

                                   FORM S-3

                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933

                                --------------

                                                           
  AmerisourceBergen Corporation              Delaware                        23-3079390
 AmeriSource Health Corporation              Delaware                        23-2546940
     AmeriSource Corporation                 Delaware                        23-2353106
                                   (State or Other Jurisdiction
  (Exact name of Registrant as          of Incorporation or               (I.R.S. Employer
    specified in its charter)              Organization)                 Identification No.)


                                --------------
                         1300 Morris Drive, Suite 100
                          Chesterbrook, PA 19087-5594
  (Address, Including Zip Code, and Telephone Number, Including Area Code, of
                   Registrant's Principal Executive Offices)

                                --------------
                           William D. Sprague, Esq.
                 Vice President, General Counsel and Secretary
                         AmerisourceBergen Corporation
                         1300 Morris Drive, Suite 100
                          Chesterbrook, PA 19087-5594
                                (610) 727-7000
 (Name, address including zip code, and telephone number, including area code,
                             of agent for service)

                                --------------
                                With Copies to:
                            Craig L. Godshall, Esq.
                                    Dechert
                           4000 Bell Atlantic Tower
                               1717 Arch Street
                          Philadelphia, PA 19103-2793
                                (215) 994-4000

                                --------------

  Approximate date of commencement of proposed sale to the public: As soon as
practicable after the effective date of this Registration Statement.


  If the only securities being registered on this Form are being offered
pursuant to dividend or interest reinvestment plans, please check the
following box. [_]


  If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities being offered only in connection with dividend or
interest reinvestment plans, check the following box. [X]

  If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following
box and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. [_]

  If this form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [_]

  If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. [_]

                                --------------

                        CALCULATION OF REGISTRATION FEE
-------------------------------------------------------------------------------
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 Title of Each Class of                Proposed Maximum Proposed Maximum  Amount of
    Securities to be      Amount to be Aggregate Price     Aggregate     Registration
       Registered          Registered    Per Unit(1)     Offering Price      Fee
-------------------------------------------------------------------------------------
                                                             
5% Convertible
 Subordinated Notes due
 December 1, 2007 of
 AmeriSource Health
 Corporation and
 AmerisourceBergen
 Corporation............  $300,000,000       100%         $300,000,000   $75,000 (1)
-------------------------------------------------------------------------------------
Common Stock of
 AmerisourceBergen
 Corporation, par value
 $.01 per share.........  5,663,730(2)        --               --           --(3)
-------------------------------------------------------------------------------------
Guarantee by AmeriSource
 Corporation............       --             --               --           --(4)
-------------------------------------------------------------------------------------


-------------------------------------------------------------------------------
(1)   Pursuant to Rule 429 under the Securities Act, this Registration
      Statement contains a combined prospectus that relates to $300,000,000 of
      5% Convertible Subordinated Notes due December 1, 2007 issued by
      AmeriSource Health Corporation and previously registered on Registration
      Statement No. 333-56538 on Form S-3, filed by AmeriSource Health
      Corporation and AmeriSource Corporation on March 5, 2001, for which
      notes AmerisourceBergen Corporation has assumed the obligations of
      AmeriSource Health Corporation. A registration fee of $75,000 was
      previously paid with the prior Registration Statement.
(2)   Plus such additional indeterminate number of shares as may become
      issuable upon conversion of the 5% Convertible Subordinated Notes due
      2007 registered hereunder by means of adjustment to the conversion price
      applicable thereto.
(3)   The shares of common stock registered hereunder are issuable upon
      conversion of the 5% Convertible Subordinated Notes due 2007 registered
      hereunder. Pursuant to Rule 457(i) under the Securities Act, there is no
      filing fee with respect to the shares of common stock issuable upon
      conversion.
(4)   Pursuant to Rule 457(n) under the Securities Act, there is no filing fee
      with respect to the Subsidiary Guarantee.


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                          [LOGO OF AMERISOURCEBERGEN]

PROSPECTUS


                         AmerisourceBergen Corporation

                      AmeriSource Health Corporation


                       $300,000,000 Principal Amount of
            5% Convertible Subordinated Notes Due December 2007 and
    5,663,730 Shares of Common Stock Issuable Upon Conversion of the Notes

  AmeriSource Health Corporation issued the 5% Convertible Subordinated Notes
in a private placement in December 2000. On August 29, 2001, AmeriSource
Health Corporation and Bergen Brunswig Corporation completed a business
combination in which AmeriSource and Bergen became wholly-owned subsidiaries
of a new parent company named AmerisourceBergen Corporation. In the merger,
each outstanding share of AmeriSource common stock was converted into one
share of AmerisourceBergen common stock and each share of Bergen common stock
was converted into 0.37 shares of AmerisourceBergen common stock. As a result,
the notes are convertible into shares of AmerisourceBergen common stock.

  This prospectus will be used by selling securityholders to resell their
notes and the common stock issuable upon conversion of their notes at market
prices prevailing at the time of sale, fixed or varying prices determined at
the time of sale, or at negotiated prices. The selling securityholders may
sell the notes or the common stock directly to purchasers or through
underwriters, broker-dealers or agents, who may receive compensation in the
form of discounts or commissions. We will not receive any proceeds from this
offering.

  The notes are convertible into shares of AmerisourceBergen's common stock at
any time before their maturity or their prior redemption or repurchase by
AmeriSource. The notes will mature on December 1, 2007. The conversion rate is
18.8791 shares for each $1,000 principal amount of notes, subject to
adjustment in certain circumstances. This is equivalent to a conversion price
of approximately $52.97 per share.

  AmerisourceBergen or AmeriSource will pay interest on the notes on June 1
and December 1 of each year. The first interest payment was made on June 1,
2001. The notes are subordinated in right of payment to all of our existing
and future senior debt. The notes are unconditionally guaranteed on a
subordinated basis by AmerisourceBergen's indirect wholly-owned subsidiary,
AmeriSource Corporation. In connection with the merger, AmerisourceBergen
became a co-obligor with AmeriSource under the 5% Convertible Subordinated
Notes. The notes will be issued only in denominations of $1,000 and integral
multiples of $1,000.

  On or after December 3, 2004, AmeriSource has the option to redeem all or a
portion of the notes that have not been previously converted at the redemption
prices set forth in this prospectus. A holder has the option, subject to
certain conditions, to require AmeriSource to repurchase any notes held by it
in the event of a "Change in Control," as described in this prospectus, at a
price equal to 100% of the principal amount of the notes plus accrued interest
to the date of repurchase. The merger, in which AmeriSource and Bergen became
subsidiaries of AmerisourceBergen, did not constitute a Change in Control.

  We have not applied for listing of the notes on any securities exchange or
for quotation through any automated quotation system. The notes are eligible
for trading in the Private Offerings, Resale and Trading Through Automated
Linkages (PORTAL) market of the National Association of Securities Dealers,
Inc. AmerisourceBergen common stock is traded on the New York Stock Exchange
under the symbol "ABC". The closing price of the common stock on the New York
Stock Exchange on September 5, 2001 was $65.47 per share.

                                ---------------

    The securities offered hereby involve a high degree of risk. See "Risk
                         Factors" beginning on page 9.

                                ---------------

  Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if
this prospectus is truthful or complete. Any representation to the contrary is
a criminal offense.

                  This prospectus is dated September 6, 2001


  You should rely only on the information contained in or incorporated by
reference in this prospectus. We have not authorized anyone to provide you
with different information. We are not making an offer of these securities in
any state where the offer is not permitted. You should not assume that the
information contained in or incorporated by reference in this prospectus is
accurate as of any date other than the date on the front of this prospectus.

                               TABLE OF CONTENTS



                                                                            Page
                                                                            ----
                                                                         
WHERE YOU CAN FIND MORE INFORMATION........................................   2
FORWARD-LOOKING STATEMENTS.................................................   3
SUMMARY....................................................................   5
RISK FACTORS...............................................................   9
USE OF PROCEEDS............................................................  14
RATIO OF EARNINGS TO FIXED CHARGES.........................................  15
DESCRIPTION OF THE NOTES...................................................  16
CERTAIN UNITED STATES FEDERAL INCOME AND ESTATE TAX CONSEQUENCES...........  32
DESCRIPTION OF CAPITAL STOCK...............................................  37
SELLING SECURITYHOLDERS....................................................  40
PLAN OF DISTRIBUTION.......................................................  45
LEGAL MATTERS..............................................................  46
EXPERTS....................................................................  47


                      WHERE YOU CAN FIND MORE INFORMATION

  AmerisourceBergen files, and AmeriSource and Bergen have filed, reports,
proxy statements, information statements and other information with the
Securities and Exchange Commission. You may read and copy this information,
for a copying fee, at the Commission's Public Reference Room at 450 Fifth
Street, N.W., Washington, D.C. 20549, and at the regional offices of the
Commission located at Citicorp Center, 500 West Madison Street, Suite 1400,
Chicago, Illinois 60661 and Seven World Trade Center, Suite 1300, New York,
New York 10048. Please call the Commission at 1-800-SEC-0330 for more
information on its public reference rooms. Commission filings are also
available to the public from commercial document retrieval services and at the
web site maintained by the Commission at http://www.sec.gov.

  AmerisourceBergen common stock is traded on the New York Stock Exchange and,
therefore, the information AmerisourceBergen files with the Commission may
also be inspected at the offices of the New York Stock Exchange, located at 20
Broad Street, New York, NY 10005.

  The Commission allows us to "incorporate by reference" information into this
prospectus, which means that we can disclose important information to you by
referring to another document filed separately with the Commission. The
information incorporated by reference is deemed to be part of this prospectus,
except for information superseded by this prospectus. This prospectus
incorporates by reference the documents set forth below that AmeriSource,
Bergen and AmerisourceBergen have previously filed with the Commission. These
documents contain important information about AmeriSource, Bergen and
AmerisourceBergen.

  .  AmeriSource's Quarterly Report on Form 10-Q for the quarter ended June
     30, 2001;

  .  AmeriSource's Quarterly Report on Form 10-Q for the quarter ended March
     31, 2001;

  .  AmeriSource's Quarterly Report on Form 10-Q for the quarter ended
     December 31, 2000;

  .  AmeriSource's Annual Report on Form 10-K for the year ended September
     30, 2000;

  .  AmeriSource's Current Report on Form 8-K dated August 27, 2001;



                                       2


  .  AmeriSource's Current Report on Form 8-K dated July 30, 2001;

  .  AmeriSource's Current Report on Form 8-K dated March 27, 2001;

  .  AmeriSource's Current Report on Form 8-K dated March 19, 2001;

  .  AmeriSource's Current Report on Form 8-K dated December 14, 2000;

  .  AmeriSource's Current Report on Form 8-K dated December 7, 2000;

  .  AmeriSource's Current Report on Form 8-K dated December 4, 2000;

  .  AmeriSource's Proxy Statement on Schedule 14A dated January 26, 2001;

  .  Bergen's Quarterly Report on Form 10-Q for the quarter ended June 30,
     2001;

  .  Bergen's Quarterly Report on Form 10-Q for the quarter ended March 31,
     2001;

  .  Bergen's Quarterly Report on Form 10-Q for the quarter ended December
     31, 2000;

  .  Bergen's Annual Report on Form 10-K for the year ended September 30,
     2000;


  .  Bergen's Current Report on Form 8-K dated August 27, 2001;


  .  Bergen's Current Report on Form 8-K dated July 30, 2001;

  .  Bergen's Current Report on Form 8-K dated July 18, 2001;

  .  Bergen's Current Report on Form 8-K dated March 19, 2001;


  .  Bergen's Proxy Statement on Schedule 14A dated January 12, 2001;

  .  AmerisourceBergen's Registration Statement on Form S-4 dated May 23,
     2001, including the final proxy statement-prospectus contained therein
     at the time of effectiveness;

  .  AmerisourceBergen's Current Report on Form 8-K dated August 30, 2001;


  .  AmerisourceBergen's Current Report on Form 8-K dated August 29, 2001;


  .  AmerisourceBergen's Current Report on Form 8-K dated August 1, 2001.

  This prospectus also incorporates by reference all documents that may be
filed by AmerisourceBergen, AmeriSource or Bergen with the Commission under
Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act after the
date of this prospectus and prior to the termination of this offering.

  If you are a stockholder, we may have sent you some of the documents
incorporated by reference, but you can obtain any of them through us or the
Commission. Documents incorporated by reference are available from us without
charge, except exhibits, unless we have specifically incorporated by reference
an exhibit into a document that this prospectus incorporates. Stockholders may
obtain documents incorporated by reference into this prospectus by requesting
them in writing or by telephone from:

  AmerisourceBergen Corporation or AmeriSource Corporation, Attention: General
Counsel, 1300 Morris Drive, Suite 100, Chesterbrook, Pennsylvania 19087-5594
Telephone: (610) 727-7000.

                          FORWARD-LOOKING STATEMENTS

  This prospectus includes forward-looking statements within the meaning of
the Private Securities Litigation Reform Act of 1995. These statements relate
to analyses and other information that are based on forecasts of future
results and estimates of amounts not yet determinable. These statements also
relate to our future prospects, developments and business strategies. The
statements contained in this prospectus that are not statements of historical
fact may include forward-looking statements that involve a number of risks and
uncertainties.

  We have used the words "anticipate," "believe," "could," "estimate,"
"expect," "intend," "may," "plan," "predict," "project," "will" and similar
terms and phrases, including references to assumptions, in

                                       3


this prospectus to identify forward-looking statements. These forward-looking
statements are made based on our management's expectations and beliefs
concerning future events affecting us and are subject to uncertainties and
factors relating to our operations and business environment, all of which are
difficult to predict and many of which are beyond our control, that could
cause our actual results to differ materially from those matters expressed in
or implied by these forward-looking statements. The following factors are
among those that may cause actual results to differ materially from our
forward-looking statements:

  .  acquisitions and dispositions;

  .  changes in general economic, business and industry conditions;

  .  changes in pharmaceutical manufacturer pricing and distribution
     policies;

  .  changes in political and social conditions and local regulations;

  .  significant litigation;

  .  changes in sales mix;

  .  competition;

  .  disruptions of established supply channels;

  .  degree of acceptance of new products;

  .  difficulty of forecasting sales at various times in various markets;

  .  the availability, terms and deployment of capital; and

  .  the other factors discussed below under the heading "Risk Factors" and
     elsewhere in this prospectus.

  All of our forward-looking statements should be considered in light of these
factors and other factors set forth in "Risk Factors" and elsewhere in this
prospectus or incorporated by reference in this prospectus. We undertake no
obligation to update our forward-looking statements or risk factors to reflect
new information, future events or otherwise.

                                       4


                                    SUMMARY

  The following summary should be read in conjunction with, and is qualified in
its entirety by, the more detailed information appearing elsewhere in this
prospectus. Unless the context otherwise requires:

  .  "we," "us," "AmerisourceBergen" and "the Company" refer to
     AmerisourceBergen Corporation and its subsidiaries on a consolidated
     basis.

  .  "AmeriSource" refers to AmeriSource Health Corporation and its
     subsidiaries on a consolidated basis.

  .  "Bergen" refers to Bergen Brunswig Corporation and its subsidiaries on a
     consolidated basis.

                               AmerisourceBergen

  We are a leading national wholesale distributor of pharmaceutical products
and related healthcare services and solutions with pro forma operating revenue
(excluding bulk shipments) of approximately $32 billion, pro forma adjusted
earnings before interest expense, taxes, depreciation and amortization of
approximately $620 million and pro forma operating income of approximately $462
million for the twelve-month period ended March 31, 2001.



  In March of 2001, AmeriSource and Bergen announced their intent to combine in
a merger-of-equals to form our company. On August 29, 2001, AmeriSource and
Bergen completed the merger. The merger will enable us to significantly enhance
our competitive position with:


  .  enhanced scale of operations;

  .  operating and administrative cost savings;

  .  improved purchasing efficiencies;

  .  improved working capital management; and

  .  broadened product offering.

  As a result of the merger, we expect to achieve estimated cost savings of
approximately $125 million per year by the end of the third year following the
consummation of the merger from, among other things, the consolidation of
distribution facilities and related working capital improvements, the
elimination of duplicative administrative functions and generic inventory
purchasing efficiencies. We also expect to benefit from lower financing costs
as a result of the combination.

  Our greater scale of operations enhances our competitive position in our core
wholesale pharmaceutical distribution business through improved access to
capital, enhanced purchasing efficiencies and a broader service offering to our
customers. We have several initiatives to provide additional value-added
services to our customers, including pharmaceutical packaging, management
information and consulting services and specialty pharmaceutical product
distribution and services.


  Our businesses operate in two segments. The first segment, pharmaceutical
distribution, includes our core wholesale pharmaceutical drug distribution
business, ASD Specialty Healthcare--our pharmaceutical alternate site
distribution business and American Health Packaging--our pharmaceutical
repackaging business. Pharmaceutical distribution also includes a number of
smaller specialty units in areas such as management reimbursement consulting
services and third party logistics services for pharmaceutical manufacturers.
Our second operating segment is PharMerica, a leading national provider of
institutional pharmacy services in long-term care and alternate site settings.
PharMerica also provides mail-order pharmacy services to chronically and
catastrophically ill patients under workers' compensation programs.

                                       5



  We are attractively positioned in the market as the only national wholesale
pharmaceutical distributor exclusively focused on pharmaceutical product
distribution, services and solutions. We serve the following major market
segments:

  .  acute care hospitals and health systems;

  .  independent retail pharmacies;

  .  the alternate site market; and

  .  national and regional retail pharmacy chains.

  We currently serve customers through a geographically diverse network of
distribution centers in the United States. We are typically the primary source
of supply for pharmaceutical and related products to our customers. We offer a
broad range of solutions to our customers and suppliers designed to enhance the
efficiency and effectiveness of their operations, allowing them to improve the
delivery of healthcare to patients and consumers and lower overall costs in the
pharmaceutical supply chain.

  In the alternate site market, we supply pharmaceuticals and other related
products and services to the oncology, nephrology, vaccine, plasma and other
specialty healthcare markets. We serve a continuum of customers including
physicians' offices and clinics, skilled nursing facilities, mail-order
facilities, assisted living centers and chronically ill patients. We also
provide plasma products to acute care hospitals.

  Our principal executive offices are located at 1300 Morris Drive, Suite 100,
Chesterbrook, Pennsylvania 19087-5594 and our western management center is
located at 4000 Metropolitan Drive, Orange, California 92868-3510. Our
telephone number is (610) 727-7000 and our website is
http://www.amerisourcebergen.net. Any Internet addresses provided in this
prospectus are for information purposes only and are not intended to be
hyperlinks. Accordingly, no information in any of these Internet addresses is
included herein.


                                       6


                                  The Offering



                              
Securities offered.............. $300,000,000 aggregate principal amount of 5%
                                 Convertible Subordinated Notes and 5,663,730
                                 shares of common stock issuable upon
                                 conversion of the notes.

Interest........................ We will pay interest on the notes semi-
                                 annually on June 1 and December 1 of each
                                 year, commencing June 1, 2001.

Guarantor....................... Our subsidiary, AmeriSource Corporation, has
                                 fully and unconditionally guaranteed the
                                 notes on a subordinated basis.

Conversion...................... You may convert each note into common stock
                                 at any time on or before December 1, 2007 at
                                 a conversion rate of 18.8791 shares of common
                                 stock per $1,000 principal amount of notes,
                                 which is equivalent to a conversion price of
                                 approximately $52.97 per share, subject to
                                 adjustment in certain events.

Subordination................... The notes are subordinated to our present and
                                 future senior indebtedness. AmeriSource
                                 Corporation's obligations under the
                                 subsidiary guarantee are subordinated to all
                                 existing and future senior indebtedness of
                                 AmeriSource Corporation. The notes are also
                                 effectively subordinated in right of payment
                                 to all indebtedness and other liabilities of
                                 our subsidiaries (other than AmeriSource and
                                 AmeriSource Corporation). Neither we nor our
                                 subsidiaries are limited from incurring
                                 additional debt, including senior
                                 indebtedness, under the indenture.

Optional redemption by           AmeriSource may redeem the notes, at its
 AmeriSource.................... option, in whole or in part, on or after
                                 December 3, 2004, at the redemption prices
                                 set forth in this prospectus plus accrued and
                                 unpaid interest.

Repurchase at option of holders  If a change in control of AmerisourceBergen
 upon change in a control....... Corporation occurs, each note holder will
                                 have the right, subject to certain conditions
                                 and restrictions, to require us to repurchase
                                 the notes held by them at 100% of their
                                 principal amount, plus accrued interest to
                                 the repurchase date. This purchase price may
                                 be paid in cash or in shares of our common
                                 stock valued at 95% of the average closing
                                 sales prices for the five trading days
                                 immediately preceding and including the third
                                 day prior to the repurchase date.

Use of proceeds................. We will not receive any of the proceeds from
                                 the sale by any selling securityholder of the
                                 notes or the underlying common stock.



                                       7



                                  Risk Factors

  An investment in the notes involves risks. Before you invest, you should
consider the risk factors described on pages 9 through 14 of this prospectus.

                                       8


                                 RISK FACTORS

  An investment in our notes or our common stock involves a high degree of
risk. You should carefully consider the following risk factors and other
information contained in and incorporated by reference into this prospectus
before investing in our notes or our common stock. The trading price of our
notes and our common stock could decline due to any of these risks, and you
may lose all or part of your investment.

Our substantial indebtedness could adversely affect our financial health and
adversely impact our ability to repay the notes.

  We are highly leveraged and we and our subsidiaries will be permitted to
incur substantial additional indebtedness in the future. See "Description of
the Notes."


  Our substantial indebtedness could have important consequences to you. For
example, it could:

  .  make it more difficult for us to satisfy our obligations with respect to
     the notes;

  .  increase our vulnerability to general adverse economic and industry
     conditions;

  .  limit our ability to obtain additional financing to fund future working
     capital, capital expenditures, and other general corporate requirements,
     or to carry out other aspects of our business plan;

  .  require us to dedicate a substantial portion of our cash flow from
     operations to the payment of principal of, and interest on, our
     indebtedness, thereby reducing the availability of such cash flow to
     fund working capital, capital expenditures, or other general corporate
     purposes, or to carry out other aspects of our business plan;

  .  limit our flexibility in planning for, or reacting to, changes in our
     business and the industry; and

  .  place us at a competitive disadvantage compared to our competitors that
     have less debt.

To service our indebtedness, we will require a significant amount of cash. Our
ability to generate cash depends on many factors beyond our control.

  Our ability to make payments on and to refinance our indebtedness, including
the notes, and to fund planned capital expenditures and efforts will depend on
our ability to generate cash in the future. This, to a certain extent, is
subject to general economic, financial, competitive, legislative, regulatory
and other factors that are beyond our control.

  Based on our current level of operations and anticipated cost savings and
operating improvements, we believe that cash flow from operations and
available cash, together with available borrowings under our new credit
facility, will be adequate to meet our future liquidity needs for at least the
next few years. We may, however, need to refinance all or a portion of the
principal amount of the notes on or prior to maturity.

  We cannot assure you, however, that our business will generate sufficient
cash flow from operations, that anticipated revenue growth and operating
improvements will be realized or that future borrowings will be available in
an amount sufficient to enable us to service our indebtedness, including these
notes, or to fund our other liquidity needs. In addition, we cannot assure you
that we will be able to refinance any of our indebtedness, including these
notes, on commercially reasonable terms or at all.

The market price of our common stock and the notes may fluctuate
significantly, which may result in losses for investors.

  The stock market and the price of our common stock may be subject to
volatile fluctuations based on general economic and market conditions,
industry trends and company performance. The market price for our common stock
may also be affected by our ability to meet analysts' expectations. Failure to
meet such expectations, even slightly, could have an adverse effect on the
market price of our common stock. In the past, following periods of volatility
in the market price of a company's securities, securities class action
litigation has often been instituted against such a company. If similar
litigation were instituted against us, it could result in substantial costs
and

                                       9


diversion of our management's attention and resources, which could have an
adverse effect on our business. Because of the volatility, we may fail to meet
the expectations of our stockholders or of securities analysts at some time in
the future, and our stock price, and therefore the price our notes, could
decline as a result.

AmerisourceBergen and AmeriSource are holding companies and rely on dividends
from their subsidiaries to make payments on the notes.


  Substantially all of our properties are owned by, and substantially all of
our operations are conducted through, our subsidiaries. As a result, we depend
on dividends and other payments from our subsidiaries to satisfy our financial
obligations and make payments to our investors. The ability of our
subsidiaries to pay dividends and make other payments to us is subject to
certain restrictions under the terms of our debt agreements. See "Description
of the Notes--Subordination". In addition, the ability of a subsidiary to pay
dividends to us will be limited by applicable law. In the event of bankruptcy
proceedings affecting a subsidiary, to the extent we are recognized as a
creditor of that subsidiary, our claims would still be subordinate to any
security interest in or other lien on any assets of that subsidiary and to any
of its debt and other obligations that are senior to the payment of the notes.

The notes are subordinated to other debt and not secured by any of our assets,
and we may be unable to repay our obligations under the notes.

  The notes will be unsecured and subordinated in right of payment to all of
the existing and future senior debt of AmerisourceBergen and AmeriSource and
the obligations of AmeriSource Corporation under the subsidiary guarantee will
be unsecured and subordinated in right of payment to all of the existing and
future senior debt of AmeriSource Corporation. Because the notes and the
obligations of AmeriSource Corporation under the subsidiary guarantee are
subordinate to senior debt of AmerisourceBergen, AmeriSource and AmeriSource
Corporation, if we experience:


  .  bankruptcy, liquidation or reorganization;

  .  an acceleration of the notes due to an event of default under the
     indenture; or

  .  other specified events,

AmerisourceBergen, AmeriSource and/or AmeriSource Corporation, as the case may
be, will not be permitted to make payments on the notes and the subsidiary
guarantee until after we have satisfied all of our senior debt obligations.
Therefore, neither we nor AmeriSource Corporation may have sufficient assets
remaining to pay amounts due on any or all of the notes.


  The indenture for the notes does not limit our ability, or that of any of
our presently existing or future subsidiaries, to incur senior debt, other
indebtedness and other liabilities. We and AmeriSource Corporation may have
difficulty paying our obligations under the notes or the subsidiary guarantee,
as the case may be, if we, or AmeriSource Corporation, incur additional
indebtedness or other liabilities. From time to time we and our subsidiaries
may incur additional indebtedness, including senior debt, which could
adversely affect our ability to pay our obligations under the notes.

The subsidiary guarantee may be unenforceable.

  Although laws differ among various jurisdictions, a court could, under
fraudulent conveyance laws, further subordinate or avoid the subsidiary
guarantee if it found that the subsidiary guarantee was incurred with actual
intent to hinder, delay or defraud creditors or that AmeriSource Corporation
did not receive fair consideration or reasonably equivalent value for the
subsidiary guarantee and that AmeriSource Corporation was any of the
following:

  .  insolvent or was rendered insolvent because of the subsidiary guarantee;

  .  engaged in a business or transaction for which its remaining assets
     constituted unreasonably small capital; or

  .  intended to incur, or believed that it would incur, debts beyond its
     ability to pay at maturity.

                                      10


  If a court voided the subsidiary guarantee as the result of a fraudulent
conveyance, or held it unenforceable for any other reason, holders of the
notes would cease to have a claim against AmeriSource Corporation based on the
subsidiary guarantee and would be solely creditors of AmeriSource and
AmerisourceBergen.

The assumption of the notes by AmerisourceBergen may be unenforceable.

  Although laws differ among various jurisdictions, a court could, under
fraudulent conveyance laws, further subordinate or avoid the assumption of the
notes by AmerisourceBergen if it found that the assumption was incurred with
actual intent to hinder, delay or defraud creditors or that AmerisourceBergen
did not receive fair consideration or reasonably equivalent value for the
assumption and that AmerisourceBergen was any of the following:

  .  insolvent or was rendered insolvent because of the assumption;

  .  engaged in a business or transaction for which its remaining assets
     constituted unreasonably small capital; or

  .  intended to incur, or believed that it would incur, debts beyond its
     ability to pay at maturity.

  If a court voided the assumption as the result of a fraudulent conveyance,
or held it unenforceable for any other reason, holders of the notes would
cease to have a claim against AmerisourceBergen based on the assumption and
would be solely creditors of AmeriSource.

We may be unable to repay or repurchase the notes.

  At maturity, the entire outstanding principal amount of the notes will
become due and payable. In addition, if we experience a change in control, as
defined in "Description of the Notes--Repurchase at Option of Holders Upon a
Change in Control", each holder of the notes may require us to repurchase all
or a portion of that holder's notes. At maturity or if a change in control
occurs, we may not have sufficient funds or may be unable to arrange for
additional financing to pay the principal amount or repurchase price due.
Under the terms of the indenture for the notes, we may elect, if we meet
certain conditions, to pay the repurchase price with shares of common stock.
Any future borrowing arrangements or agreements relating to senior debt to
which we become a party may contain restrictions on, or prohibitions against,
our repayments or repurchases of the notes. If the maturity date or change in
control occurs at a time when our other arrangements prohibit us from repaying
or repurchasing the notes, we could try to obtain the consent of the lenders
under those arrangements, or we could attempt to refinance the borrowings that
contain the restrictions. If we do not obtain the necessary consents or
refinance these borrowings, we will be unable to repay or repurchase the
notes. In that case, our failure to repurchase any tendered notes or repay the
notes due upon maturity would constitute an event of default under the
indenture. Any such default, in turn, may cause a default under the terms of
our senior debt. As a result, in those circumstances, the subordination
provisions of the indenture would, absent a waiver, prohibit any repayment or
repurchase of the notes until we pay the senior debt in full.

There may be no public market for the notes.

  While the outstanding notes are eligible for trading in the Private
Offering, Resale, and Trading through Automated Linkages (PORTAL) Market of
the National Association of Securities Dealers, Inc., a screen-based automated
market for trading securities for qualified institutional buyers, there is no
public trading market for the notes. Although the initial purchasers of the
notes have advised us that they intend to make a market in the notes, they are
not obligated to do so and may discontinue their market-making activities at
any time without notice. Consequently, we do not know if any market for the
notes will develop, or if one does develop, that it will continue for any
period of time. If an active market for the notes fails to develop or
continue, this failure could harm the trading price and liquidity of the
notes. We do not intend to apply for listing of the notes on any securities
exchange or any automated quotation system.

AmerisourceBergen may not realize all of the anticipated benefits of the
merger.

  The success of the merger will depend in part on our ability to realize the
anticipated synergies of $125 million per year by the end of the third year of
the existence of AmerisourceBergen and growth opportunities

                                      11


from integrating the businesses of AmeriSource and Bergen. Our success in
realizing these synergies, cost savings and growth opportunities, and the
timing of this realization, depends on the successful integration of
AmeriSource's and Bergen's operations. Even if we are able to integrate the
business operations of AmeriSource and Bergen successfully, we cannot assure
you that this integration will result in the realization of the full benefits
of the synergies, cost savings and growth opportunities that we currently
expect to result from this integration or that these benefits will be achieved
within the anticipated time frame. For example, the elimination of duplicative
costs may not be possible or may take longer than anticipated and the benefits
from the merger may be offset by costs incurred in integrating the companies.

Intense competition may erode our profit margins.

  The wholesale distribution of pharmaceuticals and related healthcare
services is highly competitive. We compete primarily with the following:

  .  national wholesale distributors of pharmaceuticals such as Cardinal
     Health, Inc. and McKesson Corporation;

  .  regional and local distributors of pharmaceuticals;

  .  chain drugstores that warehouse their own pharmaceuticals;

  .  manufacturers who distribute their products directly to customers; and

  .  other specialty distributors.

  Some of our competitors have greater financial resources than we have.
Competitive pressures have contributed to a decline in AmeriSource's and
Bergen's pharmaceutical wholesale drug distribution gross profit margins on
operating revenue from 5.2% in fiscal 1996 to 4.3% in fiscal 2000 on a
combined basis. This trend may continue and our business could be adversely
affected as a result.

  PharMerica faces competitive pressure from other market participants that
are significantly larger than it is and that have significantly greater
financial resources than it does. These competitive pressures could lead to a
decline in gross profit margins for PharMerica in the future. In addition,
there are relatively few barriers to entry in the local markets served by
PharMerica, and PharMerica may encounter substantial competition from new
local market entrants. These factors could adversely affect PharMerica's
business in the future.

The changing United States healthcare environment may impact our revenue and
income.

  Our products and services are intended to function within the structure of
the healthcare financing and reimbursement system currently existing in the
United States. In recent years, the healthcare industry has undergone
significant changes in an effort to reduce costs and government spending.
These changes include an increased reliance on managed care, cuts in Medicare
funding affecting our healthcare provider customer base, consolidation of
competitors, suppliers and customers, and the development of large,
sophisticated purchasing groups. We expect the healthcare industry to continue
to change significantly in the future. Some of these potential changes, such
as a reduction in governmental support of healthcare services or adverse
changes in legislation or regulations governing prescription drug pricing,
healthcare services or mandated benefits, may cause healthcare industry
participants to greatly reduce the amount of our products and services they
purchase or the price they are willing to pay for our products and services.
Changes in pharmaceutical manufacturers' pricing or distribution policies
could also significantly reduce our income.

Our operating revenue and profitability may suffer upon our loss of, or the
bankruptcy or insolvency of, a significant customer.

  During the fiscal year ended September 30, 2000 and the six-month period
ended March 31, 2001, sales to the Veterans Administration accounted for 7.3%
and 7.6%, respectively, of our pro forma operating revenue. In addition, we
have contracts with group purchasing organizations ("GPOs") which represent a
concentration of buying power among multiple healthcare providers. While we
believe the risk of default by a federal government

                                      12


agency is minimal and the credit risk with a GPO contract is spread among the
members of the GPO that purchase products from the Company, loss of a major
federal government customer or GPO could lead to a significant reduction in
revenue. We otherwise have no individual customer that accounted for more than
4.3% of our pro forma fiscal 2000 operating revenue.

Failure in our information technology systems could significantly disrupt our
operations, which could reduce our customer base and result in lost revenue.

  Our success depends, in part, on the continued and uninterrupted performance
of our information technology, or IT, systems. Our computer systems are
vulnerable to damage from a variety of sources, including telecommunications
failures, malicious human acts and natural disasters. Moreover, despite
network security measures, some of our servers are potentially vulnerable to
physical or electronic break-ins, computer viruses and similar disruptive
problems. Despite the precautions we have taken, unanticipated problems
affecting our systems could cause failures in our IT systems. Sustained or
repeated system failures that interrupt our ability to process test orders,
deliver test results or perform tests in a timely manner would adversely
affect our reputation and result in a loss of customers and net revenue.

  In addition, the wholesale drug distribution businesses of AmeriSource and
Bergen were based on different IT systems. We are in the process of evaluating
the differing systems and intend to use a common IT system in the future. This
process is complex and will take several years to complete. During systems
conversions of this type, workflow may be temporarily interrupted, which may
cause interruptions in customer service. In addition, the implementation
process, including the transfer of databases and master files to new data
centers, presents significant conversion risks which could cause failures in
our IT systems and disrupt our operations.

Our operations may suffer if government regulations regarding pharmaceuticals
change.

  The healthcare industry is highly regulated at the local, state and federal
level. Consequently, we are subject to the risk of changes in various local,
state, federal and international laws, which include the operating and
security standards of the United States Drug Enforcement Administration, or
DEA, the Food and Drug Administration, or FDA, various state boards of
pharmacy and comparable agencies. These changes may affect our operations,
including distribution of prescription pharmaceuticals (including certain
controlled substances), operation of pharmacies and packaging of
pharmaceuticals. A review of our business by regulatory authorities may result
in determinations that could adversely affect the operations of the business.

If we fail to comply with extensive laws and regulations in respect of
healthcare fraud, we could suffer penalties or be required to make significant
changes to our operations.

  We are subject to extensive and frequently changing local, state and federal
laws and regulations relating to healthcare fraud. The federal government
continues to strengthen its position and scrutiny over practices involving
healthcare fraud affecting the Medicare, Medicaid and other government
healthcare programs. Contractual relationships with pharmaceutical
manufacturers and healthcare providers subject our business to provisions of
the federal Social Security Act which, among other things, (i) preclude
persons from soliciting, offering, receiving or paying any remuneration in
order to induce the referral of a patient for treatment or for inducing the
ordering or purchasing of items or services that are in any way paid for by
Medicare, Medicaid or other government-sponsored healthcare programs and (ii)
impose a number of restrictions upon referring physicians and providers of
designated health services under Medicare and Medicaid programs. Legislative
provisions relating to healthcare fraud and abuse give federal enforcement
personnel substantially increased funding, powers and remedies to pursue
suspected fraud and abuse. While we believe that we are in material compliance
with all applicable laws, many of the regulations applicable to us, including
those relating to marketing incentives offered by pharmaceutical suppliers,
are vague or indefinite and have not been interpreted by the courts. They may
be interpreted or applied by a prosecutorial, regulatory or judicial authority
in a manner that could require us to make changes in our operations. If we
fail to comply with applicable laws and regulations, we could suffer civil and
criminal penalties, including the loss of licenses or our ability to
participate in Medicare, Medicaid and other federal and state healthcare
programs.

                                      13


If key managers leave the Company, our operating results may be adversely
affected.

  We depend on our senior management. If some of these employees leave us,
operating results could be adversely affected. We cannot be assured that we
will be able to retain these or any other key employees.

Federal and state laws that protect patient health information may increase
our costs and limit our ability to collect and use that information.

  Our activities subject us to numerous federal and state laws and regulations
governing the collection, dissemination, use, security and confidentiality of
patient-identifiable health information, including the federal Health
Insurance Portability and Accountability Act of 1996, or HIPAA, and related
rules and regulations, or Privacy Laws. For example, as part of PharMerica's
pharmaceutical dispensing, medical record keeping, third party billing and
other services, we collect and maintain patient-identifiable health
information, which activities may trigger certain requirements under the
Privacy Laws. The costs associated with our efforts to comply with the Privacy
Laws could be substantial. Moreover, if we fail to comply with certain Privacy
Laws, we could suffer civil and criminal penalties. We can provide no
assurance that the costs incurred in complying, or penalties we may incur for
failure to comply, with the Privacy Laws will not have a material effect on
us.


Our growth may be limited if we are not able to implement our acquisition
strategy.

  Since 1995, and prior to the merger of AmeriSource and Bergen, each of
AmeriSource and Bergen completed several acquisitions. Through these
acquisitions and other investments, AmeriSource and Bergen expanded their
respective geographic presence and breadth of service offerings. We expect to
continue to acquire companies as an element of our growth strategy. However,
we may not be able to identify suitable acquisition candidates or to complete
acquisitions on favorable terms. We also may not be able to successfully
integrate acquired businesses in a timely or efficient manner.


                                USE OF PROCEEDS

  We will not receive any proceeds from the sale by any selling securityholder
of the notes or the underlying common stock.

                                      14


                      RATIO OF EARNINGS TO FIXED CHARGES

                               AmerisourceBergen

  The following table summarizes the ratios of earnings to fixed charges for
AmerisourceBergen which were calculated using summary unaudited pro forma
consolidated statement of operations data for the year ended September 30,
2000, and the six months ended March 31, 2001. The summary unaudited pro forma
consolidated statement of operations data used in the calculations were
prepared under the purchase method of accounting as if the merger between
AmeriSource and Bergen and the related financing transactions had been
completed on October 1, 1999. We have included this information only for
purposes of illustration, and it does not necessarily indicate what the ratios
of earnings to fixed charges would have been if the merger and the related
financing transactions had actually been completed on October 1, 1999.
Moreover, this information does not necessarily indicate what the future
ratios of earnings to fixed charges will be. You should read this table in
conjunction with the "AmerisourceBergen Corporation Unaudited Pro Forma
Consolidated Condensed Financial Information" included in the Current Report
on Form 8-K filed by AmerisourceBergen on August 1, 2001, which is
incorporated herein by reference.




                                                                      Six Months
                                                         Year Ended     Ended
                                                        September 30, March 31,
                                                            2000         2001
                                                                
Ratio of earnings to fixed charges(1)..................      2.1         2.6

---------------------
(1) The pro forma ratio of earnings to fixed charges for the nine months ended
    June 30, 2001 will be included in a Current Report on Form 8-K to be filed
    by AmerisourceBergen pursuant to the requirements of Item 2 of Form 8-K
    and, upon filing of such Form 8-K, will be incorporated herein by
    reference.

  The above ratios of earnings to fixed charges have been computed by dividing
our earnings from continuing operations before income taxes, distribution on
preferred securities of subsidiary trust and fixed charges, by the fixed
charges. For purposes of these ratios, fixed charges consist of interest,
whether expensed or capitalized, amortization of deferred financing costs,
distributions on trust preferred securities and the portion of rent expense
representative of interest. The ratios are derived from pro forma financial
information that gives effect to the issuance of $500 million Senior Notes due
2008.


                                  AmeriSource



                         Period From
                         October 1,   Fiscal Year   Fiscal Year   Fiscal Year   Fiscal Year   Fiscal Year
                           2000 to       Ended         Ended         Ended         Ended         Ended
                          June 30,   September 30, September 30, September 30, September 30, September 30,
                            2001         2000          1999          1998          1997          1996
                                                                           
Ratio of earnings to
 fixed charges..........     5.2          4.3           3.6           2.3           2.7           2.6


  The above ratios of earnings to fixed charges have been computed by dividing
AmeriSource's earnings from continuing operations before income taxes,
extraordinary loss and fixed charges, by the fixed charges. For purposes of
these ratios, fixed charges consist of interest expense and the portion of
rent expense representative of interest.

                                      15


                           DESCRIPTION OF THE NOTES

  AmeriSource issued the notes and AmeriSource Corporation issued the
subsidiary guarantee under a document called the "Indenture." On August 29,
2001, AmerisourceBergen, AmeriSource, AmeriSource Corporation and Bank One
Trust Company, N.A., as Trustee (the "Trustee") executed a First Supplemental
Indenture to have AmerisourceBergen become a co-obligor of the notes and to
provide for the conversion of the notes into AmerisourceBergen common stock.
The Indenture and the First Supplemental Indenture are collectively referred
to in this "Description of the Notes" as the Indenture. The Indenture, the
notes and the subsidiary guarantee are governed by New York law. Because this
section is a summary, it does not describe every aspect of the notes, the
subsidiary guarantee and the Indenture. This summary is subject to and
qualified in its entirety by reference to all of the provisions of the
Indenture, including definitions of certain terms used in the Indenture. For
example, in this section we use capitalized words to signify defined terms
that have been given special meaning in the Indenture. We describe the meaning
of only the more important terms. Wherever we refer to particular defined
terms, those defined terms are incorporated by reference here. In this
section, references to AmerisourceBergen refer to AmerisourceBergen and not
its subsidiaries, references to AmeriSource refer to AmeriSource and not its
subsidiaries and references to "we," "our" or "us" refer to AmerisourceBergen
and AmeriSource (or, as the context requires, either AmerisourceBergen or
AmeriSource) and not their respective subsidiaries.


General

  The notes are general, unsecured obligations of AmerisourceBergen and
AmeriSource. The notes are subordinated, which means that they rank behind
certain of our indebtedness as described below. The notes are limited to
$300,000,000 aggregate principal amount. We are required to repay the
principal amount of the notes in full on December 1, 2007. The notes bear
interest at the rate of 5% per annum. We will pay interest on the notes on
June 1 and December 1 of each year, commencing on June 1, 2001.


  A holder of notes may convert the notes into shares of AmerisourceBergen
common stock initially at the conversion rate of 18.8791 shares per $1,000 in
principal amount of notes at any time before the close of business on December
1, 2007, unless the notes have been previously redeemed or repurchased. The
conversion rate may be adjusted as described below.

  AmeriSource may redeem the notes at its option at any time on or after
December 3, 2004, in whole or in part, at the redemption prices set forth
below under "--Optional Redemption," plus accrued and unpaid interest to the
redemption date. If there is a Change in Control of AmerisourceBergen, you may
have the right to require us to repurchase your notes as described below under
"--Repurchase at Option of Holders Upon a Change in Control."


Form, Denomination, Transfer, Exchange and Book-Entry Procedures


  The notes were issued:

  .  only in fully registered form;

  .  without interest coupons; and

  .  in denominations of $1,000 and greater multiples.

  The notes that are sold under this prospectus will be evidenced by one or
more global notes which are deposited with the Trustee as custodian for The
Depository Trust Company ("DTC") and registered in the name of Cede & Co.
("Cede"), as nominee of DTC. Except as set forth below, record ownership of
the global note may be transferred, in whole or in part, only to another
nominee of DTC or to a successor of DTC or its nominee.


                                      16


  The global note will not be registered in the name of any person, or
exchanged for notes that are registered in the name of any person, other than
DTC or its nominee unless either of the following occurs:

  .  DTC notifies us that it is unwilling, unable or no longer qualified to
     continue acting as the depositary for the global note; or

  .  an event of default with respect to the notes represented by the global
     note has occurred and is continuing.

  In those circumstances, DTC will determine in whose names any securities
issued in exchange for the global note will be registered.

  DTC or its nominee will be considered the sole owner and holder of the
global note for all purposes, and as a result:

  .  you cannot get notes registered in your name if they are represented by
     the global note;

  .  you cannot receive certificated (physical) notes in exchange for your
     beneficial interest in the global notes;

  .  you will not be considered to be the owner or holder of the global note
     or any note it represents for any purpose; and

  .  all payments on the global note will be made to DTC or its nominee.

  The laws of some jurisdictions require that certain kinds of purchasers (for
example, certain insurance companies) can only own securities in definitive
(certificated) form. These laws may limit your ability to transfer your
beneficial interests in the global note to these types of purchasers.

  Only institutions (such as a securities broker or dealer) that have accounts
with DTC or its nominee (called "participants") and persons that may hold
beneficial interests through participants can own a beneficial interest in the
global note. The only place where the ownership of beneficial interests in the
global note will appear and the only way the transfer of those interests can
be made will be on the records kept by DTC (for their participants' interests)
and the records kept by those participants (for interests of persons held by
participants on their behalf).


  Secondary trading in bonds and notes of corporate issuers is generally
settled in clearinghouse (that is, next-day) funds. In contrast, beneficial
interests in a global note usually trade in DTC's same-day funds settlement
system, and settle in immediately available funds. We make no representations
as to the effect that settlement in immediately available funds will have on
trading activity in those beneficial interests.

  We will make cash payments of interest on and principal of and the
redemption or repurchase price of the global note, as well as any payment of
Liquidated Damages, to Cede, the nominee for DTC, as the registered owner of
the global note. We will make these payments by wire transfer of immediately
available funds on each payment date.

  We have been informed that DTC's practice is to credit participants'
accounts on the payment date with payments in amounts proportionate to their
respective beneficial interests in the notes represented by the global note as
shown on DTC's records, unless DTC has reason to believe that it will not
receive payment on that payment date. Payments by participants to owners of
beneficial interests in notes represented by the global note held through
participants will be the responsibility of those participants, as is now the
case with securities held for the accounts of customers registered in "street
name".

  We will send any redemption notices to Cede. We understand that if less than
all the notes are being redeemed, DTC's practice is to determine by lot the
amount of the holdings of each participant to be redeemed.

  We also understand that neither DTC nor Cede will consent or vote with
respect to the notes. We have been advised that under its usual procedures,
DTC will mail an "omnibus proxy" to us as soon as possible after the

                                      17


record date. The omnibus proxy assigns Cede's consenting or voting rights to
those participants to whose accounts the notes are credited on the record date
identified in a listing attached to the omnibus proxy.

  Because DTC can only act on behalf of participants, who in turn act on
behalf of indirect participants, the ability of a person having a beneficial
interest in the principal amount represented by the global note to pledge the
interest to persons or entities that do not participate in the DTC book-entry
system, or otherwise take actions in respect of that interest, may be affected
by the lack of a physical certificate evidencing its interest.

  DTC has advised us that it will take any action permitted to be taken by a
holder of notes (including the presentation of notes for exchange) only at the
direction of one or more participants to whose account with DTC interests in
the global note are credited and only in respect of such portion of the
principal amount of the notes represented by the global note as to which such
participant or participants has or have given such direction.

  DTC has also advised us as follows: DTC is a limited purpose trust company
organized under the laws of the State of New York, a member of the Federal
Reserve System, a "clearing corporation" within the meaning of the Uniform
Commercial Code, as amended, and a "clearing agency" registered pursuant to
the provisions of Section 17A of the Securities and Exchange Act of 1934, as
amended (the "Exchange Act"). DTC was created to hold securities for its
participants and facilitate the clearance and settlement of securities
transactions between participants through electronic book-entry changes in
accounts of its participants. Participants include securities brokers and
dealers, banks, trust companies and clearing corporations and may include
certain other organizations. Certain of such participants (or their
representatives), together with other entities, own DTC. Indirect access to
the DTC system is available to other entities such as banks, brokers, dealers
and trust companies that clear through or maintain a custodial relationship
with a participant, either directly or indirectly.

  The policies and procedures of DTC, which may change periodically, will
apply to payments, transfers, exchanges and other matters relating to
beneficial interests in the global note. We and the Trustee have no
responsibility or liability for any aspect of DTC's or any participants'
records relating to beneficial interests in the global note, including for
payments made on the global note, and we and the Trustee are not responsible
for maintaining, supervising or reviewing any of those records.

Conversion Rights

  A holder of notes may, at its option, convert any portion of the principal
amount of any note that is an integral multiple of $1,000 into shares of
AmerisourceBergen common stock at any time on or prior to the close of
business on the maturity date, unless the notes have been previously redeemed
or repurchased, at a conversion rate of 18.8791 shares of common stock per
$1,000 principal amount of notes. The conversion rate is equivalent to a
conversion price of approximately $52.97 per share. The right of a holder of
notes to convert a note called for redemption or delivered for repurchase will
terminate at the close of business on the redemption date or repurchase date
for that note, unless we default in making the payment due upon redemption or
repurchase.

  A holder of notes may convert all or part of any note by delivering the note
at the Corporate Trust Office of the Trustee in the Borough of Manhattan, The
City of New York, accompanied by a duly signed and completed notice of
conversion, a copy of which may be obtained by the Trustee. The conversion
date will be the date on which the note and the duly signed and completed
notice of conversion are so delivered.

  As promptly as practicable on or after the conversion date,
AmerisourceBergen will issue and deliver to the Trustee a certificate or
certificates for the number of full shares of AmerisourceBergen common stock
issuable upon conversion, together with payment in lieu of any fraction of a
share. The certificate will then be sent by the Trustee to the conversion
agent for delivery to the holder. The shares of AmerisourceBergen common stock
issuable upon conversion of the notes will be fully-paid and nonassessable and
will rank equally with the other shares of AmerisourceBergen common stock.

                                      18


  If a holder of notes surrenders a note for conversion on a date that is not
an Interest Payment Date, the holder will not be entitled to receive any
interest for the period from the next preceding Interest Payment Date to the
conversion date, except as described below in this paragraph. Any note
surrendered for conversion during the period from the close of business on any
Regular Record Date to the opening of business on the next succeeding Interest
Payment Date (except notes (or portions thereof) called for redemption on a
redemption date or to be repurchased on a repurchase date for which the right
to convert would terminate during such period) must be accompanied by payment
of an amount equal to the interest payable on such Interest Payment Date on
the principal amount of notes being surrendered for conversion. In the case of
any note which has been converted after any Regular Record Date but before the
next succeeding Interest Payment Date, interest payable on such Interest
Payment Date shall be payable on such Interest Payment Date notwithstanding
such conversion, and such interest shall be paid to the holder of such note on
such Regular Record Date.

  No other payment or adjustment for interest, or for any dividends in respect
of AmerisourceBergen common stock, will be made upon conversion. Holders of
AmerisourceBergen common stock issued upon conversion will not be entitled to
receive any dividends payable to holders of common stock as of any record time
or date before the close of business on the conversion date. We will not issue
fractional shares upon conversion. Instead, we will pay cash based on the
market price of AmerisourceBergen common stock at the close of business on the
conversion date.


  A holder of notes will not be required to pay any stamp or similar taxes or
duties relating to the issue or delivery of AmerisourceBergen common stock on
conversion but will be required to pay any stamp or similar tax or duty
relating to any transfer involved in the issue or delivery of
AmerisourceBergen common stock in a name other than that of the holder.
Certificates representing shares of AmerisourceBergen common stock will not be
issued or delivered unless all stamp or similar taxes and duties, if any,
payable by the holder have been paid. The conversion of notes into
AmerisourceBergen common stock may be considered a taxable exchange for
federal income tax purposes. See "Certain United States Federal Income and
Estate Tax Consequences--Tax Consequences to U.S. Holders."


  The conversion rate will be subject to adjustment for, among other things:

  .  dividends (and other distributions) payable in AmerisourceBergen common
     stock on shares of AmerisourceBergen capital stock,

  .  the issuance to all holders of AmerisourceBergen common stock of rights,
     options or warrants entitling them to subscribe for or purchase
     AmerisourceBergen common stock at less than the then Current Market
     Price of such common stock (determined as provided in the Indenture) as
     of the record date for stockholders entitled to receive such rights,
     options or warrants,

  .  subdivisions, combinations and reclassifications of AmerisourceBergen
     common stock,

  .  distributions to all holders of AmerisourceBergen common stock of
     evidences of indebtedness of AmerisourceBergen, shares of capital stock,
     cash or assets (including securities, but excluding those dividends,
     rights, options, warrants and distributions referred to above, dividends
     and distributions paid exclusively in cash and distributions upon
     mergers or consolidations discussed below),

  .  distributions consisting exclusively of cash (excluding any cash portion
     of distributions referred to in the immediately preceding clause, or
     cash distributed upon a merger or consolidation to which the next
     succeeding paragraph applies) to all holders of AmerisourceBergen common
     stock in an aggregate amount that, combined together with (1) other such
     all-cash distributions made within the preceding 365-day period in
     respect of which no adjustment has been made and (2) any cash and the
     fair market value of other consideration payable in connection with any
     tender offer by AmerisourceBergen or any of its subsidiaries for
     AmerisourceBergen common stock concluded within the preceding 365-day
     period in respect of which no adjustment has been made, exceeds 10% of
     AmerisourceBergen's market capitalization (being the product of the
     Current Market Price per share of the common stock on the record date
     for such distribution and the number of shares of common stock then
     outstanding), and

                                      19



  .  the successful completion of a tender offer made by AmerisourceBergen or
     any of its subsidiaries for AmerisourceBergen common stock which
     involves an aggregate consideration that, together with (1) any cash and
     other consideration payable in a tender offer by AmerisourceBergen or
     any of its subsidiaries for AmerisourceBergen common stock expiring
     within the 365-day period preceding the expiration of such tender offer
     in respect of which no adjustment has been made and (2) the aggregate
     amount of any such all-cash distributions referred to in the immediately
     preceding clause above to all holders of AmerisourceBergen common stock
     within the 365-day period preceding the expiration of such tender offer
     in respect of which no adjustments have been made, exceeds 10% of
     AmerisourceBergen's market capitalization on the expiration of such
     tender offer.


  AmerisourceBergen reserves the right to effect such increases in the
conversion rate in addition to those required by the foregoing provisions as
AmerisourceBergen considers to be advisable in order that any event treated
for United States federal income tax purposes as a dividend of stock or stock
rights will not be taxable to the recipients. AmerisourceBergen will not be
required to make any adjustment to the conversion rate until the cumulative
adjustments amount to 1.0% or more of the conversion rate. AmerisourceBergen
will compute all adjustments to the conversion rate and will give notice by
mail to holders of the registered notes of any adjustments.

  In case of any consolidation or merger of AmerisourceBergen with or into
another entity or any merger of another entity into AmerisourceBergen (other
than a merger which does not result in any reclassification, conversion,
exchange or cancellation of AmerisourceBergen common stock), or in case of any
sale or transfer of all or substantially all of AmerisourceBergen's assets,
each note then outstanding will become convertible only into the kind and
amount of securities, cash and other property receivable upon such
consolidation, merger, sale or transfer by a holder of the number of shares of
common stock into which the notes were convertible immediately prior to the
consolidation or merger or sale or transfer.

  AmerisourceBergen may increase the conversion rate for any period of at
least 20 days, upon at least 15 days notice, if the AmerisourceBergen Board of
Directors determines that the increase would be in AmerisourceBergen's best
interest. The Board of Directors' determination in this regard will be
conclusive. AmerisourceBergen will give holders of notes at least 15 days'
notice of such an increase in the conversion rate. Any increase, however, will
not be taken into account for purposes of determining whether the closing
price of AmerisourceBergen common stock exceeds the conversion price by 105%
in connection with an event which otherwise would be a Change in Control as
defined below.


  If at any time AmerisourceBergen makes a distribution of property to
AmerisourceBergen's stockholders that would be taxable to such stockholders as
a dividend for United States federal income tax purposes, such as
distributions of evidences of indebtedness or assets of AmerisourceBergen, but
generally not stock dividends on common stock or rights to subscribe for
common stock, and, pursuant to the anti-dilution provisions of the Indenture,
the number of shares into which notes are convertible is increased, that
increase may be deemed for United States federal income tax purposes to be the
payment of a taxable dividend to holders of notes. See "Certain United States
Federal Income and Estate Tax Consequences--Tax Consequences to U.S. Holders."

Subsidiary Guarantee

  AmeriSource Corporation, which is a direct subsidiary of AmeriSource and an
indirect subsidiary of AmerisourceBergen, has fully and unconditionally
guaranteed, on a subordinated basis, our obligations under the notes. The
obligations of AmeriSource Corporation under the subsidiary guarantee is
subordinated to the prior payment in full in cash or cash equivalents of all
Senior Debt of AmeriSource Corporation. The subordination provisions
applicable to the subsidiary guarantee are substantially the same as the
subordination provisions applicable to the notes. The obligations of
AmeriSource Corporation under the subsidiary guarantee are limited as
necessary to seek to prevent such subsidiary guarantee from constituting a
fraudulent conveyance under applicable law.

                                      20


  AmeriSource Corporation may not sell or otherwise dispose of all or
substantially all of its assets, or consolidate with or merge with or into,
another person unless:

  .  immediately after giving effect to that transaction, no default or event
     of default exists under the Indenture; and

  .  the person acquiring the property in any similar sale or disposition or
     the person formed by or surviving any similar consolidation or merger
     assumes all the obligations of AmeriSource Corporation pursuant to a
     supplemental indenture satisfactory to the trustee.

  AmeriSource Corporation will be released from its subsidiary guarantee:

  .  in connection with any sale or other disposition of all or substantially
     all of its assets, if the disposition is to us; or

  .  in connection with any sale of all of its capital stock, if the person
     acquiring the capital stock assumes all the obligations of AmeriSource
     Corporation pursuant to a supplemental indenture satisfactory to the
     trustee.

Subordination

  The notes are subordinated and, as a result, the payment of the principal,
any premium and interest (including Liquidated Damages) on the notes,
including amounts payable on any redemption or repurchase, will be
subordinated to the prior payment in full, in cash or other payment
satisfactory to holders of Senior Debt, of all of our senior debt. The
obligations of AmeriSource Corporation under the subsidiary guarantee is
subordinated to all existing and future senior debt of AmeriSource
Corporation.

  "Senior Debt" is defined in the Indenture with respect to each of
AmerisourceBergen, AmeriSource and AmeriSource Corporation to mean: the
principal of (and premium, if any) and interest (including all interest
accruing subsequent to the commencement of any bankruptcy or similar
proceeding, whether or not a claim for post-petition interest is allowable as
a claim in any such proceeding) on, and all fees and other amounts payable in
connection with, the following, whether absolute or contingent, secured or
unsecured, due or to become due, outstanding on the date of the Indenture or
thereafter created, incurred or assumed:

  .  indebtedness evidenced by a credit or loan agreement, note, bond,
     debenture or other written obligation,

  .  obligations for money borrowed and obligations under the receivables
     securitization facility,

  .  obligations evidenced by a note or similar instrument given in
     connection with the acquisition of any businesses, properties or assets
     of any kind,

  .  obligations (1) as lessee under leases required to be capitalized on the
     balance sheet of the lessee under generally accepted accounting
     principles or (2) as lessee under other leases for facilities, capital
     equipment or related assets, whether or not capitalized, entered into or
     leased for financing purposes,

  .  obligations under interest rate and currency swaps, caps, floors,
     collars, hedge agreements, forward contracts or similar agreements or
     arrangements,

  .  obligations with respect to letters of credit, bankers' acceptances and
     similar facilities (including reimbursement obligations with respect to
     the foregoing),

  .  obligations issued or assumed as the deferred purchase price of property
     or services (but excluding trade accounts payable and accrued
     liabilities arising in the ordinary course of business),

  .  obligations of the type referred to in the above clauses of another
     person and all dividends of another person, the payment of which, in
     either case, we have assumed or guaranteed, or for which we are
     responsible or liable, directly or indirectly, jointly or severally, as
     obligor, guarantor or otherwise, or which are secured by a lien on our
     property, and

                                      21


  .  renewals, extensions, modifications, replacements, restatements and
     refundings of, or any indebtedness or obligation issued in exchange for,
     any such indebtedness or obligation described in the above clauses of
     this definition.

Senior Debt will not include the notes or any other indebtedness or obligation
if its terms or the terms of the instrument under which or pursuant to which
it is issued expressly provide that it is not superior in right of payment to
the notes or the obligations under the subsidiary guarantee.

  AmerisourceBergen or AmeriSource may not make any payment on account of
principal, premium or interest (including Liquidated Damages, if any) on the
notes, or redemption or repurchase of the notes, if either of the following
occurs:

  .  AmerisourceBergen or AmeriSource, as the case may be, defaults in its
     obligations to pay principal, premium, interest or other amounts on its
     Senior Debt, including a default under any redemption or repurchase
     obligation, and the default continues beyond any grace period that
     AmerisourceBergen or AmeriSource may have to make those payments; or


  .  any other default occurs and is continuing on any Designated Senior Debt
     of AmerisourceBergen or AmeriSource, as the case may be, and (1) the
     default permits the holders of the Designated Senior Debt to accelerate
     its maturity and (2) the Trustee has received a notice (a "Payment
     Blockage Notice") of the default from AmerisourceBergen or AmeriSource,
     the holder of such debt or such other person permitted to give such
     notice under the Indenture.


  If payments of the notes have been blocked by a payment default on Senior
Debt, payments on the notes may resume when the payment default has been cured
or waived or ceases to exist. If payments on the notes have been blocked by a
nonpayment default, payments on the notes may resume on the earlier of (1) the
date the nonpayment default is cured or waived or ceases to exist or (2) 179
days after the Payment Blockage Notice is received.

  No nonpayment default that existed on the day a Payment Blockage Notice was
delivered to the Trustee can be used as the basis for any subsequent Payment
Blockage Notice. In addition, once a holder of Designated Senior Debt has
blocked payment on the notes by giving a Payment Blockage Notice, no new
period of payment blockage can be commenced pursuant to a subsequent Payment
Blockage Notice until both of the following are satisfied:

  .  365 days have elapsed since the effectiveness of the immediately prior
     Payment Blockage Notice; and

  .  all scheduled payments of principal, any premium and interest with
     respect to the notes that have come due have been paid in full in cash.

  "Designated Senior Debt" means our obligations under the Liquidity Credit
Facility, the Receivables Securitization Facility and the Revolving Credit
Facility and under any other particular Senior Debt in which the instrument
creating or evidencing the same or the assumption or guarantee thereof (or
related agreements or documents to which we are a party), whether or not
executed contemporaneously with the issuance of such Senior Debt expressly
provides that such Senior Debt shall be "Designated Senior Debt" for purposes
of this prospectus (provided that such instrument, agreement or other document
may place limitations and conditions on the right of such Senior Debt to
exercise the rights of Designated Senior Debt).

  "Liquidity Credit Facility" means the credit facility created pursuant to
the Liquidity Facility Credit Agreement dated as of October 3, 2000 among
AmeriSource Corporation, as borrower, AmeriSource Health Corporation, as a
guarantor, the lenders identified therein and Bank of America, N.A., as
administrative agent, as such agreement has been or may be amended,
supplemented, restated, extended, renewed or otherwise modified from time to
time and includes any agreement (and all successor agreements thereto)
extending the maturity of, refinancing or otherwise restructuring all or any
portion of the indebtedness under such agreement or any successor agreement.

                                      22



  "Receivables Securitization Facility" means a credit facility which was
entered into pursuant to the Receivables Purchase Agreement, dated May 14,
1999 among AmeriSource Receivables Financial Corporation, as seller,
AmeriSource Corporation, as servicer, AmeriSource Health Corporation, as
guarantor, Delaware Funding Corporation, as buyer, and Morgan Guaranty Trust
Company of New York, as administrative agent, as such agreement has been or
may be amended, supplemented, restated, extended, renewed or otherwise
modified from time to time and includes any agreement (and all successor
agreements thereto) extending the maturity of, refinancing or otherwise
restructuring all or any portion of the indebtedness under such agreement or
any successor agreement.


  "Revolving Credit Facility" means a credit facility created pursuant to the
Revolving Credit Agreement dated as of January 8, 1997 among AmeriSource
Corporation, as borrower, AmeriSource Health Corporation, as a guarantor, the
lenders identified therein and Bank of America, N.A., as administrative agent,
as such agreement has been or may be amended, supplemented, restated,
extended, renewed or otherwise modified from time to time and includes any
agreement (and all successor agreements thereto) extending the maturity of,
refinancing or otherwise restructuring all or any portion of the indebtedness
under such agreement or any successor agreement.

  In addition, upon any acceleration of the principal due on the notes as a
result of an Event of Default or payment or distribution of our assets to
creditors upon any dissolution, winding up, liquidation or reorganization,
whether voluntary or involuntary, marshaling of assets, assignment for the
benefit of creditors, or in bankruptcy, insolvency, receivership or other
similar proceedings, all principal, premium, if any, interest and other
amounts due on all of our Senior Debt must be paid in full before a holder of
notes is entitled to receive any payment. By reason of such subordination, in
the event of insolvency, our creditors who are holders of our Senior Debt are
likely to recover more, ratably, than a holder of notes is, and a holder of
notes will likely experience a reduction or elimination of payments on the
notes.

  The Indenture does not limit our ability or the ability of AmeriSource
Corporation to incur Senior Debt or our ability or the ability of AmeriSource
Corporation or our other subsidiaries to incur any other indebtedness.

Optional Redemption

  On or after December 3, 2004, AmeriSource may redeem the notes, in whole or
in part, at the prices set forth below. If AmeriSource elects to redeem all or
part of the notes, AmeriSource will give at least 30, but no more than 60,
days notice to you.

  The redemption price, expressed as a percentage of principal amount, is as
follows for the 12-month periods beginning on December 1 of the following
years (December 3, 2004 through December 1, 2005 in the case of the first such
period):



                                                                    Redemption
               Year                                                   Price
                                                                 
               2004                                                  102.143%
               2005                                                  101.429%
               2006                                                  100.714%


and thereafter is equal to 100% of the principal amount, in each case together
with accrued interest to the date of redemption.

  No sinking fund is provided for the notes, which means that the Indenture
does not require us to redeem or retire the notes periodically.

Payment and Conversion

  We will make all payments of principal and interest on the notes by dollar
check drawn on an account maintained at a bank in The City of New York. If a
holder of notes holds registered notes with a face value

                                      23


greater than $2,000,000, at the request of the holder we will make payments of
principal or interest to the holder by wire transfer to an account maintained
by the holder at a bank in The City of New York. Payment of any interest on
the notes will be made to the person in whose name the note, or any
predecessor note, is registered at the close of business on December 1 or June
1 (whether or not a business day) immediately preceding the relevant Interest
Payment Date (a "Regular Record Date"). If a holder of notes holds registered
notes with a face value in excess of $2,000,000 and the holder would like to
receive payments by wire transfer, the holder will be required to provide the
Trustee with wire transfer instructions at least 15 days prior to the relevant
payment date.

  Payments on any global note registered in the name of DTC or its nominee
will be payable by the Trustee to DTC or its nominee in its capacity as the
registered holder under the Indenture. Under the terms of the Indenture, we
and the Trustee will treat the persons in whose names the notes, including any
global note, are registered as the owners for the purpose of receiving
payments and for all other purposes. Consequently, neither we, the Trustee nor
any of our agents or the Trustee's agents has or will have any responsibility
or liability for (1) any aspect of DTC's records or any participant's or
indirect participant's records relating to or payments made on account of
beneficial ownership interests in the global note, or for maintaining,
supervising or reviewing any of DTC's records or any participant's or indirect
participant's records relating to the beneficial ownership interests in the
global note, or (2) any other matter relating to the actions and practices of
DTC or any of its participants or indirect participants.

  We will not be required to make any payment on the notes due on any day
which is not a business day until the next succeeding business day. The
payment made on the next succeeding business day will be treated as though it
were paid on the original due date and no interest will accrue on the payment
for the additional period of time.

  Notes may be surrendered for conversion at the Corporate Trust Office of the
Trustee in the Borough of Manhattan, The City of New York. Notes surrendered
for conversion must be accompanied by appropriate notices and any payments in
respect of interest or taxes, as applicable, as described above under "--
Conversion Rights."

  We have initially appointed the Trustee as paying agent and conversion
agent. We may terminate the appointment of any paying agent or conversion
agent and appoint additional or other paying agents and conversion agents.
However, until the notes have been delivered to the Trustee for cancellation,
or moneys sufficient to pay the principal of, premium, if any, and interest on
the notes have been made available for payment and either paid or returned to
us as provided in the Indenture, the Trustee will maintain an office or agency
in the Borough of Manhattan, The City of New York for surrender of notes for
conversion. Notice of any termination or appointment and of any change in the
office through which any paying agent or conversion agent will act will be
given in accordance with "--Notices" below.

  All moneys deposited with the Trustee or any paying agent, or then held by
us, in trust for the payment of principal of, premium, if any, or interest on
any notes which remain unclaimed at the end of two years after the payment has
become due and payable will be repaid to us, and a holder of notes will then
look only to us for payment.

Repurchase at Option of Holders Upon a Change in Control

  If a Change in Control as defined below occurs, a holder of notes will have
the right, at its option, to require us to repurchase all of the notes not
previously called for redemption, or any portion of the principal amount
thereof, that is equal to $1,000 or an integral multiple of $1,000. The price
we are required to pay is 100% of the principal amount of the notes to be
repurchased, together with interest accrued to, but excluding, the repurchase
date.

                                      24



  At our option, instead of paying the repurchase price in cash, we may pay
the repurchase price in AmerisourceBergen common stock valued at 95% of the
average of the closing prices of AmerisourceBergen common stock for the five
trading days immediately preceding and including the third day prior to the
repurchase date. We may only pay the repurchase price in AmerisourceBergen
common stock if AmerisourceBergen satisfies conditions provided in the
Indenture.


  Within 30 days after the occurrence of a Change in Control, we are obligated
to give to the holders of notes notice of the Change in Control and of the
repurchase right arising as a result of the Change of Control. In addition, at
such time, we must give notice if we are exercising our option to pay the
repurchase price in AmerisourceBergen common stock. We must also deliver a
copy of this notice to the Trustee. To exercise the repurchase right, a holder
of notes must deliver on or before the 30th day after the date of our notice
irrevocable written notice to the Trustee of the holder's exercise of its
repurchase right, together with the notes with respect to which the right is
being exercised. We are required to repurchase the notes on the date that is
45 days after the date of our notice.


  A Change in Control will be deemed to have occurred at the time after the
notes are originally issued that any of the following occurs:

    (1) any person, including any syndicate or group deemed to be a "person"
  under Section 13(d)(3) of the Exchange Act, acquires beneficial ownership,
  directly or indirectly, through a purchase, merger or other acquisition
  transaction or series of transactions, of shares of AmerisourceBergen
  capital stock entitling the person to exercise 50% or more of the total
  voting power of all shares of AmerisourceBergen capital stock that is
  entitled to vote generally in elections of directors, other than an
  acquisition by AmerisourceBergen, any of its subsidiaries or any of its
  employee benefit plans; or

    (2) AmerisourceBergen merges or consolidates with or into any other
  person, any merger of another person into AmerisourceBergen, or
  AmerisourceBergen conveys, sells, transfers or leases all or substantially
  all of its assets to another Person, other than any such transaction (a)
  that does not result in any reclassification, conversion, exchange or
  cancellation of outstanding shares of AmerisourceBergen capital stock, or
  (b) pursuant to which the holders of AmerisourceBergen common stock
  immediately prior to such transaction have the entitlement to exercise,
  directly or indirectly, 50% or more of the total voting power of all shares
  of capital stock entitled to vote generally in the election of directors of
  the continuing or surviving corporation immediately after such transaction,
  or (c) which is effected solely to change AmerisourceBergen's jurisdiction
  of incorporation and results in a reclassification, conversion or exchange
  of outstanding shares of AmerisourceBergen common stock into solely shares
  of common stock.

  However, a Change in Control will not be deemed to have occurred if either
(A) the closing price per share of AmerisourceBergen common stock for any five
trading days within the period of 10 consecutive trading days ending
immediately after the later of the Change in Control or the public
announcement of the Change in Control, in the case of a Change in Control
relating to an acquisition of capital stock, or the period of 10 consecutive
trading days ending immediately before the Change in Control, in the case of a
Change in Control relating to a merger, consolidation or asset sale, equals or
exceeds 105% of the conversion price of the notes in effect on each of those
trading days, or (B) all of the consideration (excluding cash payments for
fractional shares and cash payments made pursuant to dissenters' appraisal
rights) in a merger or consolidation otherwise constituting a Change of
Control under clause (1) and/or clause (2) above consists of shares of common
stock traded on a national securities exchange or listed on the New York Stock
Exchange (or will be so traded or quoted immediately following such merger or
consolidation) and as a result of such merger or consolidation the notes
become convertible into such common stock.


  For purposes of these provisions:

  .  the conversion price is equal to $1,000 divided by the conversion rate;

  .  whether a person is a "beneficial owner" will be determined in
     accordance with Rule 13d-3 under the Exchange Act; and

                                      25


  .  "person" includes any syndicate or group that would be deemed to be a
     "person" under Section 13(d)(3) of the Exchange Act.

  Rule 13e-4 under the Exchange Act requires the dissemination of prescribed
information to securityholders in the event of an issuer tender offer and may
apply in the event that the repurchase option becomes available to the holders
of notes. We will comply with this rule to the extent it applies at that time.

  We may, to the extent permitted by applicable law, at any time purchase
notes in the open market, by tender at any price or by private agreement. Any
note that we purchase may, to the extent permitted by applicable law and
subject to restrictions contained in the purchase agreement with the Initial
Purchasers, be re-issued or resold or may, at our option, be surrendered to
the Trustee for cancellation. Any notes surrendered for cancellation may not
be re-issued or resold and will be canceled promptly.

  The definition of Change in Control includes a phrase relating to the
conveyance, transfer, sale, lease or disposition of "all or substantially all"
of AmerisourceBergen's assets. There is no precise, established definition of
the phrase "substantially all" under applicable law. Accordingly, the ability
of a holder of notes to require us to repurchase its notes as a result of
conveyance, transfer, sale, lease or other disposition of less than all of
AmerisourceBergen's assets may be uncertain.

  The foregoing provisions would not necessarily provide you with protection
if AmerisourceBergen is involved in a highly leveraged or other transaction
that may adversely affect the holders.

  Our ability to repurchase notes upon the occurrence of a Change in Control
is subject to important limitations. Some of the events constituting a Change
in Control could result in an event of default under our Senior Debt.
Moreover, a Change in Control could cause an event of default under, or be
prohibited or limited by, the terms of our Senior Debt. As a result, unless we
were to obtain a waiver, a repurchase of the notes in cash could be prohibited
under the subordination provisions of the Indenture until the Senior Debt is
paid in full. Although AmerisourceBergen has the right to repurchase the notes
with AmerisourceBergen common stock, subject to certain conditions, we cannot
assure you that we would have the financial resources, or would be able to
arrange financing, to pay the repurchase price in cash for all the notes that
might be delivered by holders of notes seeking to exercise the repurchase
right. If we were to fail to repurchase the notes when required following a
Change in Control, an Event of Default under the Indenture would occur,
whether or not such repurchase is permitted by the subordination provisions of
the Indenture. Any such default may, in turn, cause a default under our Senior
Debt. See "--Subordination".

Mergers and Sales of Assets

  We may not consolidate with or merge into any other person or convey,
transfer, sell or lease our properties and assets substantially as an entirety
to any person, and we may not permit any person to consolidate with or merge
into us or convey, transfer, sell or lease such person's properties and assets
substantially as an entirety to us unless:

  .  the person formed by such consolidation or into or with which we are
     merged or the person to which our properties and assets are so conveyed,
     transferred, sold or leased, shall be a corporation, limited liability
     company, partnership or trust organized and existing under the laws of
     the United States, any State within the United States or the District of
     Columbia and, if we are not the surviving person, the surviving person
     assumes the payment of the principal of, premium, if any, and interest
     on the notes and the performance of our other covenants under the
     Indenture, and

  .  immediately after giving effect to the transaction, no event of default,
     and no event that, after notice or lapse of time or both, would become
     an event of default, will have occurred and be continuing.

                                      26


Events of Default

  The following will be Events of Default under the Indenture:

  .  we fail to pay principal of or premium, if any, on any note when due,
     whether or not prohibited by the subordination provisions of the
     Indenture;

  .  we fail to pay any interest, including any Liquidated Damages, on any
     note when due, which failure continues for 30 days, whether or not
     prohibited by the subordination provisions of the Indenture;

  .  we fail to provide notice of a Change in Control, whether or not such
     notice is prohibited by the subordination provisions of the Indenture;

  .  we fail to perform any other covenant in the Indenture, which failure
     continues for 60 days after written notice as provided in the Indenture;

  .  any indebtedness under any bonds, debentures, notes or other evidences
     of indebtedness for money borrowed (or any guarantee thereof) by us or
     any of our significant subsidiaries in an aggregate principal amount in
     excess of $15.0 million is not paid when due either at its stated
     maturity or upon acceleration thereof, and such indebtedness is not
     discharged, or such acceleration is not rescinded or annulled, within a
     period of 30 days after notice as provided in the Indenture;

  .  certain events of bankruptcy, insolvency or reorganization involving us
     or any of our significant subsidiaries; or

  .  except as permitted by the Indenture, the subsidiary guarantee shall for
     any reason cease to be, or be asserted in writing by the AmeriSource
     Corporation or us not to be in full force and effect and enforceable in
     accordance with its terms.

  Subject to the provisions of the Indenture relating to the duties of the
Trustee in case an Event of Default shall occur and be continuing, the Trustee
will be under no obligation to exercise any of its rights or powers under the
Indenture at the request or direction of any holder, unless the holder shall
have offered reasonable indemnity to the Trustee. Subject to providing
indemnification of the Trustee, the holders of a majority in aggregate
principal amount of the outstanding notes will have the right to direct the
time, method and place of conducting any proceeding for any remedy available
to the Trustee or exercising any trust or power conferred on the Trustee.

  If an Event of Default, other than an Event of Default arising from events
of insolvency, bankruptcy or reorganization with respect to us or any of our
significant subsidiaries, occurs and is continuing, either the Trustee or the
holders of at least 25% in principal amount of the outstanding notes may,
subject to the subordination provisions of the Indenture, accelerate the
maturity of all notes. However, after such acceleration, but before a judgment
or decree based on acceleration, the holders of a majority in aggregate
principal amount of outstanding notes may, under certain circumstances,
rescind and annul the acceleration if all Events of Default, other than the
non-payment of principal of the notes which have become due solely by such
declaration of acceleration, have been cured or waived as provided in the
Indenture. If an Event of Default arising from events of insolvency,
bankruptcy or reorganization with respect to us occurs, then the principal of,
and accrued interest on, all the notes will automatically become immediately
due and payable without any declaration or other act on the part of the
holders of the notes or the Trustee. For information as to waiver of defaults,
see "--Meetings, Modification and Waiver".

  A holder of notes will not have any right to institute any proceeding with
respect to the Indenture, or for any remedy under the Indenture, unless the
holder gives the Trustee written notice of a continuing Event of Default and
the holders of at least 25% in aggregate principal amount of the outstanding
notes have made written request, and offered reasonable indemnity, to the
Trustee to institute proceedings, and the Trustee has not received from the
holders of a majority in aggregate principal amount of the outstanding notes a
direction inconsistent with the written request and shall have failed to
institute such proceeding within 60 days. However, these limitations do not
apply to a suit instituted by a holder of notes for the enforcement of payment
of the principal of, premium, if any, or interest, including Liquidated
Damages, on the holder's note on or after the

                                      27


respective due dates expressed in its note or the holder's right to convert
its note in accordance with the Indenture.

  We will be required to furnish to the Trustee annually a statement as to our
performance of certain of our obligations under the Indenture and as to any
default in such performance.

Meetings, Modification and Waiver

  The Indenture contains provision for convening meetings of the holders of
notes to consider matters affecting their interests.

  Certain limited modifications of the Indenture may be made without the
necessity of obtaining the consent of the holders of the notes. Other
modifications and amendments of the Indenture may be made, and certain past
defaults by us may be waived, either (i) with the written consent of the
holders of not less than a majority in aggregate principal amount of the notes
at the time outstanding or (ii) by the adoption of a resolution, at a meeting
of holders of the notes at which a quorum is present, by the holders of at
least 66 2/3% in aggregate principal amount of the notes represented at such
meeting. The quorum at any meeting called to adopt a resolution will be
persons holding or representing a majority in aggregate principal amount of
the notes at the time outstanding and, at any reconvened meeting adjourned for
lack of a quorum, 25% of such aggregate principal amount.

  However, a modification or amendment requires the consent of the holder of
each outstanding note affected if it would:

  .  change the stated maturity of the principal or interest of a note;

  .  reduce the principal amount of, or any premium or interest on, any note;

  .  reduce the amount payable upon a redemption or mandatory repurchase;

  .  modify the provisions with respect to the repurchase rights of holders
     of notes in a manner adverse to the holders;

  .  change the place or currency of payment on a note;

  .  impair the right to institute suit for the enforcement of any payment on
     any note;

  .  modify our obligation to maintain an office or agency in New York City;

  .  modify the subordination provisions in a manner that is adverse to the
     holders of the notes;

  .  adversely affect the right to convert the notes;

  .  modify our obligation to deliver information required under Rule 144A to
     permit resales of the notes and common stock issued upon conversion of
     the notes if we cease to be subject to the reporting requirements under
     the Exchange Act;

  .  reduce the above-stated percentage of the principal amount of the
     holders whose consent is needed to modify or amend the Indenture;

  .  reduce the percentage of the principal amount of the holders whose
     consent is needed to waive compliance with certain provisions of the
     Indenture or to waive certain defaults; or

  .  reduce the percentage required for the adoption of a resolution or the
     quorum required at any meeting of holders of notes at which a resolution
     is adopted.

  The holders of a majority in aggregate principal amount of the outstanding
notes may waive compliance by us with certain restrictive provisions of the
Indenture by written consent. Holders of a majority of the principal amount of
notes attending a meeting may also waive compliance by us with certain
restrictive provisions of the Indenture by the adoption of a resolution at the
meeting if a quorum of holders are present and certain other conditions are
met. The holders of a majority in aggregate principal amount of the
outstanding notes also may

                                      28


waive by written consent any past default under the Indenture, except a
default in the payment of principal, premium, if any, or interest.

Registration Rights

  The registration statement of which this prospectus forms a part has been
filed under the terms of a Registration Rights Agreement, which AmeriSource
entered into with the initial purchasers of the notes. In the Registration
Rights Agreement, AmeriSource and AmeriSource Corporation agree, for the
benefit of the holders of the notes and the shares of common stock issuable
upon conversion of the notes (together, the "Registrable Securities"), that
AmeriSource and AmeriSource Corporation would, at their expense:

  .  file with the SEC, within 90 days after the date the notes were
     originally issued, a shelf registration statement covering resales of
     the Registrable Securities, subject to the right to postpone the filing
     of the shelf registration statement for an additional 90 days in limited
     circumstances;

  .  use reasonable efforts to cause the shelf registration statement to be
     declared effective under the Securities Act within 180 days after the
     date the notes are originally issued, subject to the right to postpone
     having the shelf registration statement declared effective for an
     additional 90 days in limited circumstances; and

  .  use reasonable efforts to keep effective the shelf registration
     statement until two years after the date the notes are issued or, if
     earlier, until there are no outstanding Registrable Securities, which is
     referred to as the Effectiveness Period.

  AmeriSource will be permitted to suspend the use of this prospectus that is
part of the shelf registration statement in connection with the sales of
Registrable Securities during prescribed periods of time for reasons relating
to pending corporate developments, public filings with the SEC and other
events. The periods during which AmeriSource can suspend the use of the
prospectus may not, however, exceed a total of 45 days in any 90 day period or
a total of 90 days in any 365-day period. Following the effectiveness of the
registration statement of which this prospectus forms a part, AmeriSource will
provide to each holder of Registrable Securities copies of this prospectus,
notify each holder that the shelf registration statement has become effective
and take certain other actions required to permit public resales of the
Registrable Securities.

  AmeriSource may, upon written notice to all the holders of notes, postpone
having the shelf registration statement declared effective for a reasonable
period not to exceed 90 days if AmeriSource possesses material nonpublic
information the disclosure of which would have a material adverse effect on
AmeriSource and its subsidiaries taken as a whole. Notwithstanding any such
postponement, additional interest, which is referred to as Liquidated Damages,
will accrue on the notes if either of the following events, which are referred
to as Registration Defaults occurs:


  .  on or prior to 90 days following the date the notes were originally
     issued, a shelf registration statement has not been filed with the SEC;
     or

  .  on or prior to 180 days following the date the notes were originally
     issued, the shelf registration statement is not declared effective.

  In that case, Liquidated Damages will accrue on the notes from and including
the day following the Registration Default to but excluding the day on which
the Registration Default has been cured. Liquidated Damages will be paid semi-
annually in arrears, with the first semi-annual payment due on the first
Interest Payment Date following the date on which the Liquidated Damages began
to accrue.

  The rates at which Liquidated Damages will accrue will be as follows:

  .  0.25% of the principal amount per annum to and including the 90th day
     after the Registration Default; and

  .  0.50% of the principal amount per annum from and after the 91st day
     after the Registration Default.

                                      29


  In addition, the interest rate on the notes will be increased if:

  .  the shelf registration statement ceases to be effective, or AmeriSource
     otherwise prevents or restricts holders of Registrable Securities from
     making sales under the shelf registration statement, for more than 45
     days, whether or not consecutive during any 90-day period; or

  .  the shelf registration statement ceases to be effective, or AmeriSource
     otherwise prevents or restricts holders of Registrable Securities from
     making sales under the shelf registration statement, for more than 90
     days, whether or not consecutive, during any 12-month period.


  In either event, the interest rate on the notes will increase by an
additional 0.50% per annum from the 46th day of the 90-day period or the 91st
day of the 12-month period. The increased rate will continue until the earlier
of the following:

  .  the time the shelf registration statement again becomes effective or the
     holders of Registrable Securities are again able to make sales under the
     shelf registration statement, depending on which event triggered the
     increase in interest rate; or

  .  the date the Effectiveness Period expires.

  A holder who elects to sell any Registrable Securities pursuant to the shelf
registration statement will be required to be named as a selling
securityholder in this prospectus, may be required to deliver a prospectus to
purchasers, may be subject to certain civil liability provisions under the
Securities Act in connection with those sales and is bound by the provisions
of the Registration Rights Agreement that apply to a holder making such an
election, including certain indemnification provisions.

  No holder of Registrable Securities will be entitled to be named as a
selling securityholder in this prospectus, and no holder of Registrable
Securities is entitled to use this prospectus for offers and resales of
Registrable Securities at any time, unless the holder has returned a completed
and signed Notice and Questionnaire to AmeriSource.

  Beneficial owners of Registrable Securities who have not returned a Notice
and Questionnaire to AmeriSource may receive another Notice and Questionnaire
from AmeriSource upon request. Following AmeriSource's receipt of a completed
and signed Notice and Questionnaire, AmeriSource will include the Registrable
Securities covered thereby in the shelf registration statement, subject to
restrictions on the timing and number of supplements to the shelf registration
statement provided in the Registration Rights Agreement.

  AmeriSource agreed in the Registration Rights Agreement to use its
reasonable efforts to cause the shares of common stock issuable upon
conversion of the notes to be listed on the New York Stock Exchange. However,
if the AmerisourceBergen common stock is not then listed on the New York Stock
Exchange, AmeriSource will use its reasonable efforts to cause the shares of
common stock issuable upon conversion of the notes to be quoted or listed on
whichever market or exchange the AmerisourceBergen common stock is then quoted
or listed, upon effectiveness of the shelf registration statement.

  This summary of certain provisions of the Registration Rights Agreement may
not contain all the information important to the holders of notes. Holders of
notes may request from AmerisourceBergen or AmeriSource a copy of the
Registration Rights Agreement.

Notices

  Notice to holders of the registered notes will be given by mail to the
addresses as they appear in the security register. Notices will be deemed to
have been given on the date of such mailing.

  Notice of a redemption of notes will be given not less than 30 nor more than
60 days prior to the redemption date and will specify the redemption date. A
notice of redemption of the notes will be irrevocable.

                                      30


Replacement of Notes

  We will replace any note that becomes mutilated, destroyed, stolen or lost
at the expense of the holder upon delivery to the Trustee of the mutilated
notes or evidence of the loss, theft or destruction satisfactory to us and the
Trustee. In the case of a lost, stolen or destroyed note, indemnity
satisfactory to the Trustee and us may be required at the expense of the
holder of the note before a replacement note will be issued.

Payment of Stamp and Other Taxes

  We have paid all stamp and other duties, if any, which may have been imposed
by the United States or any political subdivision thereof or taxing authority
thereof or therein with respect to the issuance of the notes. We were not
required to make any payment with respect to any other tax, assessment or
governmental charge imposed by any government or any political subdivision
thereof or taxing authority thereof or therein.

Governing Law

  The Indenture, the notes and the subsidiary guarantee are governed by and
construed in accordance with the laws of the State of New York, United States
of America.

The Trustee

  If an Event of Default occurs and is continuing, the Trustee will be
required to use the degree of care of a prudent person in the conduct of his
own affairs in the exercise of its powers. Subject to such provisions, the
Trustee will be under no obligation to exercise any of its rights or powers
under the Indenture at the request of any of the holders of notes, unless they
shall have offered to the Trustee reasonable security or indemnity.

                                      31


       CERTAIN UNITED STATES FEDERAL INCOME AND ESTATE TAX CONSEQUENCES

  The following is a general discussion of certain U.S. federal income and
estate tax consequences to you of holding the notes and common stock issuable
upon conversion of the notes. This discussion is based upon the Internal
Revenue Code of 1986, as amended (the "Code"), U.S. Treasury Regulations
("Regulations"), Internal Revenue Service ("IRS") rulings and pronouncements,
and judicial decisions now in effect, all of which are subject to change
(possibly with retroactive effect) or different interpretation.

  This discussion is for your general information only and does not address
all aspects of U.S. federal income taxation that may be relevant to you. This
discussion does not describe the tax consequences arising under the laws of
any foreign, state or local jurisdiction, nor does it describe all of the tax
consequences to you in light of your personal circumstances (such as the U.S.
federal alternative minimum tax). It also does not address certain tax
consequences that may apply to you if you are subject to special tax rules,
such as if you are a financial institution, an insurance company, a tax-exempt
entity, a dealer in securities, if you hold the notes or common stock in
connection with a "straddle", "hedging", or "conversion" transaction for U.S.
federal income tax purposes, or if your "functional currency" is not the U.S.
dollar. This discussion assumes that you acquired our notes on their original
issuance at their original offering price and hold the notes and common stock
received upon conversion thereof as capital assets within the meaning of
Section 1221 of the Code. We have not sought any ruling from the IRS with
respect to statements made and the conclusions reached in this discussion and
there can be no assurance that the IRS will agree with our statements and
conclusions.


  YOU ARE URGED TO CONSULT YOUR OWN TAX ADVISOR REGARDING THE FEDERAL, STATE,
LOCAL AND FOREIGN TAX CONSEQUENCES OF YOUR PARTICIPATION IN THIS OFFERING, AND
YOUR OWNERSHIP AND DISPOSITION OF THE NOTES (INCLUDING CONVERSION OF THE
NOTES) OR COMMON STOCK, INCLUDING THE EFFECT THAT YOUR PARTICULAR
CIRCUMSTANCES MAY HAVE ON THE TAX CONSEQUENCES OF YOUR PARTICIPATION IN THIS
OFFERING, AS WELL AS THE CONSEQUENCES OF ANY PROPOSED CHANGE IN THE APPLICABLE
LAWS.

Tax Consequences to U.S. Holders

  The following tax discussion applies to you if you are a beneficial owner of
the notes or common stock and you are:

  .  a citizen or resident of the United States,

  .  a corporation (or other entity taxed as a corporation) created or
     organized under the laws of the United States or a political subdivision
     thereof,

  .  an estate the income of which is subject to U.S. federal income taxation
     regardless of source, or

  .  a trust if (A) a U.S. court is able to exercise primary supervision over
     the trust's administration or (B) one or more U.S. persons, as defined
     under section 7701(a)(30) of the Code, have authority to control all the
     trust's substantial decisions.

  If you are a partnership or beneficial owner of an interest in a
partnership, your tax treatment may depend upon both your status and the
partnership's status, as the case may be, and you are urged to consult your
tax advisor.


  If you are a beneficial owner of the notes or common stock not included in
the above list, you are a Non-U.S. Holder and you will generally be subject to
the rules described in "--Tax Consequences to Non-U.S. Holders" below.

  Interest on Notes. You will be taxed on interest on a note as the interest
accrues or when you actually or constructively receive it, in accordance with
your method of accounting for U.S. federal income tax purposes. We do not
believe that the notes were issued with "original issue discount" within the
meaning of the Code.

                                      32



  Conversion of Notes. The federal income tax treatment of a conversion of
notes into shares of AmerisourceBergen common stock following the Merger is
unclear.


  The IRS has ruled that a conversion of notes for stock of a parent
corporation was not a taxable exchange when the parent had become a co-obligor
on the notes with its subsidiary in connection with a prior merger, and when
the addition of the parent corporation as a co-obligor (together with other
changes to the terms of the notes) was viewed as an exchange under Section
1001 of the Code of the subsidiary's notes for new notes. However, it is not
clear from the ruling whether the IRS's conclusion regarding the tax-free
treatment of the conversion depended upon its prior conclusion, in the same
ruling, that the prior note modification was a Section 1001 exchange. If the
treatment of the modification as a Section 1001 exchange is not a pre-
requisite to this conclusion, then the conversion of notes for
AmerisourceBergen common stock should not be a taxable disposition of the
notes. If your conversion of the notes into AmerisourceBergen common stock is
not a taxable event, your tax basis in any shares of common stock received
would be equal to the tax basis in any notes you surrender, and the holding
period of those shares would include the holding period for the notes you
surrender.


  The notes (with AmerisourceBergen as co-obligor) should be viewed, for
federal income tax purposes, as merely a continuation of the AmeriSource notes
originally issued in December 2000, and the addition of AmerisourceBergen as
co-obligor should not result in a Section 1001 exchange of the notes. As a
result, the notes might not be treated, for federal income tax purposes, as
obligations of AmerisourceBergen, despite its co-obligor status. If that were
the case, (i) you would recognize gain or loss upon conversion of the notes
into AmerisourceBergen common stock, measured by the difference between the
fair market value of the common stock received and your tax basis in the notes
surrendered, and (ii) your tax basis in any shares of common stock received
would be equal to the fair market value of common stock on the date of the
conversion.

  If you receive cash in lieu of a fractional share of common stock, it will
be treated as a payment in exchange for the fractional share. You generally
will recognize capital gain or loss equal to the difference between the amount
of cash received and the amount of tax basis allocable to the fractional
share.

  HOLDERS OF NOTES SHOULD CONSULT THEIR TAX ADVISORS WITH RESPECT TO THE
POSSIBLE CONSEQUENCES OF CONVERTING NOTES INTO SHARES OF AMERISOURCEBERGEN
STOCK FOLLOWING THE MERGER.

  Adjustment of Conversion Rate. The conversion rate of the notes is subject
to adjustment in certain circumstances. See "Description of the Notes--
Conversion Rights". Under Section 305(c) of the Code, adjustments that have
the effect of increasing or decreasing your proportionate interest in our
assets or earnings (for example, an adjustment following a distribution of
property to our stockholders) may in some circumstances give rise to a deemed
distribution to you. Similarly, a failure to adjust the conversion rate of the
notes to reflect a stock dividend or other event increasing the proportionate
interest of stockholders of outstanding stock can in some instances give rise
to deemed distributions to the stockholders. The deemed distributions will be
treated as dividends, returns of capital, or capital gains in accordance with
the earnings and profits rules discussed under "--Distributions on Common
Stock" below.

  Liquidated Damages. We intend to take the position that the Liquidated
Damages described above under "Description of Notes--Registration Rights" will
be taxable to you as ordinary income in accordance with your method of
accounting for U.S. federal income tax purposes only as and if you become
entitled to or receive such Liquidated Damages, depending upon your method of
accounting. The IRS, however, may take a different position, which could
affect the timing of both your income and our deduction with respect to the
Liquidated Damages.

  Distributions on Common Stock. Distributions that you receive on common
stock will be treated as dividends for U.S. federal income tax purposes to the
extent of current or accumulated earnings and profits as determined under U.S.
federal income tax principles. If you are a U.S. corporation, you may qualify
for the dividends received deduction. If you are not a corporation, you are
not entitled to a dividends received deduction.

                                      33


  To the extent, if any, that you receive a distribution that would otherwise
constitute a dividend for U.S. federal income tax purposes but that exceeds
our current and accumulated earnings and profits, the excess will be treated
first as a non-taxable return of capital reducing your basis in the common
stock. To the extent that such a distribution also exceeds your basis in the
common stock, the excess will be treated as capital gain from the sale or
exchange of your common stock.

  Sale or Exchange of Notes or Common Stock. In general, subject to the
discussion under "--Market Discount" below, you will recognize capital gain or
loss on the sale, redemption, retirement or other disposition of a note
measured by the difference between the amount of cash and the fair market
value of any property received (except to the extent attributable to the
payment of accrued interest) and your adjusted tax basis in the note. In
general, subject to the discussion under "--Market Discount" below, if you
receive common stock upon conversion of a note, you will recognize gain or
loss upon a subsequent sale, exchange, redemption or other disposition of the
common stock under rules similar to the computation of gain or loss on
disposition of the notes. However, special rules may apply to a redemption of
common stock which may result in the proceeds of the redemption being treated
as a dividend. In general, if you are not a corporation, and have held the
notes or common stock for more than one year, you will be subject to a maximum
federal tax rate of 20% on the capital gains resulting from the disposition.

  Market Discount. If you acquire a note other than at original issue, you may
be affected by the "market discount" provisions of the Code. For this purpose,
market discount on a note generally equals the amount, if any, by which the
stated redemption price at maturity of the note immediately after you acquire
it exceeds your adjusted tax basis in the note. Subject to a de minimis
exception, if you acquire a note with market discount and later dispose of the
note, you must treat the gain as ordinary income to the extent of the "accrued
market discount" on the note when you dispose of it, unless you have made an
election to include accrued market discount in your income on a current basis.
In general, market discount will be treated as accruing from the time you buy
it over the remaining term of the note on a straight-line basis or, at your
election, under a constant yield method. If you acquire a note at a market
discount and do not elect to include accrued market discount income currently,
and you borrowed money (or maintained outstanding debt) to finance your
purchase of the note, you may be required to defer the deduction of a portion
of the interest on that debt until you dispose of the note in a taxable
transaction. If you acquire a note with market discount and receive common
stock upon its conversion, and you subsequently sell the common stock, you
will be required to treat as ordinary income the amount of accrued market
discount that you had not yet included in your income (if any) through the
date of conversion.

  IRS Reporting and Backup Withholding. If you are not a corporation, you may
be subject to IRS reporting and backup withholding at a rate of 30.5% (or such
lesser rate applicable after 2001) on payments of interest on the notes,
dividends on common stock, and proceeds from the sale or other disposition of
the notes or common stock, if:

  .  you fail to furnish your taxpayer identification number ("TIN"), which
     ordinarily would be your social security number,

  .  you furnish an incorrect TIN,

  .  you are notified by the IRS that you have failed to properly report
     payments of interest or dividends, or

  .  under certain circumstances, you fail to certify, under penalties of
     perjury, that you have furnished a correct TIN and have not been
     notified by the IRS that you are subject to backup withholding.

  We will also institute backup withholding on payments made to you if
instructed to do so by the IRS. If you do not provide us with a correct TIN,
you may also be subject to penalties imposed by the IRS.

  You will be allowed to claim any amounts that we withhold as a credit
against your U.S. federal income tax liability, if any. If the amount of the
backup withholding exceeds your U.S. federal income tax liability, you may
seek a refund from the IRS, provided that you follow the requisite procedures.
You should consult your

                                      34


own tax advisor regarding your qualification for exemption from backup
withholding and the procedure for obtaining such an exemption, if applicable.

Tax Consequences to Non-U.S. Holders

  The following discussion applies to you if you are a Non-U.S. Holder. Non-
U.S. Holders whose income or gain related to the notes or common stock is
effectively connected with the conduct of a U.S. trade or business will
generally be subject to the foregoing rules applicable to U.S. Holders,
subject to applicable treaty relief.

  Payments of Interest. Generally, if you or someone acting on your behalf
receives payments of interest (including for this purpose, any Liquidated
Damages) on the notes, the payments will not be subject to U.S. federal
withholding tax if:


  .  you do not actually or constructively own 10% or more of the total
     combined voting power of all classes of our stock;

  .  you are not (a) a controlled foreign corporation for U.S. federal income
     tax purposes that is related to us through stock ownership or (b) a bank
     that received the note on an extension of credit made pursuant to a loan
     agreement entered into in the ordinary course of its trade or business;
     and

  .  you provide a statement, signed under penalties of perjury, that
     includes your name and address and certifies that you are not a U.S.
     person.

  If you cannot satisfy these requirements, you will be subject to U.S.
federal withholding tax at a rate of 30% unless you qualify for a reduced rate
under a tax treaty or under certain other special circumstances. If you
qualify for a reduced withholding rate, you will have to declare that you are
so qualified by providing us with the appropriate form, signed under penalties
of perjury.

  Adjustment of Conversion Rate. The conversion rate of the notes may be
adjusted in certain circumstances. See "Description of Notes--Conversion
Rights". Any such adjustment could give rise to a deemed distribution to you
in the same manner as was described for U.S. Holders. See "Tax Consequences to
U.S. Holders--Adjustment of Conversion Rate" above. If so, the deemed
distribution would be subject to the rules described below regarding
withholding of U.S. federal income tax on dividends. See "--Distributions on
Common Stock" below.

  Distributions on Common Stock. If you receive distributions on common stock,
they will be dividends for U.S. federal income tax purposes to the extent of
our current or accumulated earnings and profits, as determined under U.S.
federal income tax principles, and will be subject to U.S. federal withholding
tax at a rate of 30% unless you qualify for a reduced rate under a tax treaty
or under certain other special circumstances. If you qualify for a reduced
withholding rate, you will have to declare that you are so qualified by
providing us with the appropriate form, signed under penalties of perjury.

  Sale or Exchange of Notes or Common Stock. In general, you will not be
subject to U.S. federal withholding tax on gain recognized upon the sale or
other disposition (including a redemption) of a note or common stock received
upon conversion thereof unless:

  .  you are a nonresident alien individual present in the United States for
     183 days or more in the taxable year in which gain is realized, and
     certain other conditions are satisfied;

  .  you are subject to tax pursuant to the provisions of U.S. tax law
     applicable to certain U.S. expatriates; or

  .  we are or have been a United States real property holding corporation
     ("USRPHC") for U.S. federal income tax purposes at any time within the
     shorter of the five year period preceding the disposition or your
     holding period.

  We believe we are not presently, and are not likely to become, a USRPHC.

                                      35


  U.S. Estate Tax. If you own notes when you die and you are not a citizen or
resident (as specifically defined for U.S. federal estate tax purposes) of the
United States at the time of your death, the notes will not be includible in
your gross estate for U.S. federal estate tax purposes, provided that, at the
time of your death, you do not own, actually or constructively, 10% or more of
the total combined voting power of all classes of our stock, and any payments
with respect to the notes would not have been effectively connected with your
conduct of a trade or business in the United States. However, the common stock
you own will be includible in your gross estate for U.S. federal estate tax
purposes as a result of your death, and subject to applicable treaty
limitations, may be subject to U.S. federal estate tax.

  IRS Reporting and Backup Withholding. We must report annually to the IRS and
to you any interest and dividends paid with respect to any notes or common
stock that you hold, and whether they are subject to U.S. federal withholding
tax or exempt from such tax under an applicable treaty or the Code. We also
report to the IRS and to you any income that we paid to you and that is exempt
from federal withholding tax because it is effectively connected with your
U.S. trade or business. However, you will not be subject to IRS reporting or
backup withholding if we have received the appropriate forms from you or on
your behalf and provided that we do not have actual knowledge that you are in
fact a U.S. Holder. If we pay the proceeds from the disposition of notes or
common stock to or through the U.S. office of any broker, the payment will be
subject to IRS reporting and possibly backup withholding unless you certify as
to your non-U.S. status under penalties of perjury or otherwise establish an
exemption, provided that the broker does not have actual knowledge that you
are in fact a U.S. Holder or that the conditions of any other exemption are
not, in fact, satisfied. If we pay any proceeds from the distribution of a
note or common stock to or through a non-U.S. office of a non-U.S. broker that
is not a "U.S. related person", those proceeds will not be subject to IRS
reporting or backup withholding. For this purpose, a "U.S. related person" is:

  .  a "controlled foreign corporation" for U.S. federal income tax purposes;

  .  a person 50% or more of whose gross income from all sources for the
     three-year period ending with the close of its taxable year preceding
     the payment (or for such part of the period that the broker has been in
     existence) is derived from activities that are effectively connected
     with the conduct of a U.S. trade or business, or

  .  a foreign partnership, if at any time during its tax year, one or more
     of its partners are U.S. persons (as defined in the Regulations) who in
     the aggregate hold more than 50% of the income or capital interest in
     the partnership, or if at any time during the tax year the partnership
     is engaged in a U.S. trade or business.

  If we pay proceeds from the disposition of notes or common stock to or
through a non-U.S. office of a broker that is a U.S. related person, the
Regulations require us to report on the payment unless the broker has
documentary evidence in its files that you are a Non-U.S. Holder and the
broker has no knowledge to the contrary. Backup withholding will not apply to
such payments, unless we have actual knowledge that you are a U.S. Person.

                                      36


                         DESCRIPTION OF CAPITAL STOCK

Authorized Capital Stock

  Total Shares. We are authorized to issue a total of 310,000,000 shares of
capital stock consisting of:

  .  300,000,000 shares of common stock, par value $0.01 per share; and

  .  10,000,000 shares of preferred stock, par value $0.01 per share.

  Listing. The common stock trades on the New York Stock Exchange under the
symbol "ABC." No other capital stock of AmerisourceBergen is listed.

  Preemptive Rights. The holders of our common stock and preferred stock have
no preemptive rights to purchase or subscribe for any stock or other
securities of AmerisourceBergen.

Common Stock

  Voting Rights. Each outstanding share of common stock is entitled to one
vote per share. The holders of common stock have the exclusive right to vote
for the election of directors and for all other purposes as provided by law.

  Dividends. Subject to the rights of holders of preferred stock, holders of
common stock are entitled to receive ratably on a per share basis such
dividends and other distributions in cash, stock or property of
AmerisourceBergen as may be declared by the board of directors from time to
time out of the legally available assets or funds of AmerisourceBergen. We
currently intend to pay quarterly dividends on its common stock of $0.025 per
share.

  Liquidation. Subject to the rights of holders of preferred stock, in the
event of the voluntary or involuntary liquidation, dissolution or winding up
of AmerisourceBergen, holders of common stock are entitled to receive all of
the remaining assets of AmerisourceBergen available for distribution to its
stockholders.

Preferred Stock

  General. Our board of directors is authorized to provide for the issuance of
shares of preferred stock in one or more series with various designations,
preferences, and relative, participating, optional or other special rights and
qualifications, limitations or restrictions.

  Voting. Except as required by law, or as otherwise provided by the board of
directors, the holders of preferred stock have no voting rights and will not
be entitled to any notice of meeting of stockholders.

  Dividends. Holders of preferred stock are entitled to receive, when declared
by the board of directors, out of legally available funds, dividends at the
rates fixed by the board of directors for the respective series of preferred
stock, and no more, before any dividends will be declared and paid, or set
apart for payment, on AmerisourceBergen common stock with respect to the same
dividend period.

  Liquidation. In the event of the voluntary or involuntary liquidation,
dissolution or winding up of AmerisourceBergen, holders of each series of
preferred stock are entitled to receive the amount fixed for such series plus,
in the case of any series on which dividends will have been determined by the
board of directors to be cumulative, an amount equal to all dividends
accumulated and unpaid to the date of final distribution whether or not earned
or declared before any distribution shall be paid, or set aside for payment,
to holders of common stock.

  Redemption. At the option of our board of directors, we may redeem all or
part of the shares of any series of preferred stock on such terms and
conditions fixed in the applicable preferred stock certificate of designation
for such series.

                                      37


Stockholders Rights Plans

  AmerisourceBergen. On August 27, 2001, AmerisourceBergen adopted a
stockholder rights plan pursuant to a rights agreement with Mellon Investor
Services LLC, as rights agent. Set forth below is a summary of the material
provisions of the rights agreement. The summary does not include a complete
description of all of the terms of the rights agreement.


  Exercisability of Rights. Under the AmerisourceBergen rights agreement, one
right, referred to as an AmerisourceBergen right, attaches to each share of
AmerisourceBergen common stock outstanding and, when exercisable, entitles the
registered holder to purchase from AmerisourceBergen one one-hundredth of a
share of AmerisourceBergen Series A preferred stock at an initial purchase
price of $275, subject to customary antidilution adjustments.

  The AmerisourceBergen rights will not become exercisable until the earlier
of:

  .  10 business days following a public announcement that a person has
     become the beneficial owner of 15% or more of the AmerisourceBergen
     common stock then outstanding; and

  .  10 business days, or such later date as may be determined by the board
     of directors of AmerisourceBergen, following the commencement of a
     tender offer or exchange offer that would result in a person becoming
     the beneficial owner of 15% or more of the AmerisourceBergen common
     stock then outstanding.

  Series A Preferred Stock. In connection with the creation of the
AmerisourceBergen rights, the board of directors of AmerisourceBergen
authorized the issuance of 3,000,000 shares of AmerisourceBergen preferred
stock designated as AmerisourceBergen Series A preferred stock.

  AmerisourceBergen has designed the dividend, liquidation, voting and
redemption features of the AmerisourceBergen Series A preferred stock so that
the value of one one-hundredth of a share of AmerisourceBergen Series A
preferred stock approximates the value of one share of AmerisourceBergen
common stock. Shares of AmerisourceBergen Series A preferred stock may only be
purchased after the AmerisourceBergen rights have become exercisable.

  "Flip In" Feature. In the event a person becomes the beneficial owner of 15%
or more of the AmerisourceBergen common stock outstanding, each holder of an
AmerisourceBergen right, except for such acquiring person, will have the right
to acquire, upon exercise of the AmerisourceBergen right, instead of one one-
hundredth of a share of AmerisourceBergen Series A preferred stock, shares of
AmerisourceBergen Series A preferred stock having a value equal to twice the
then current purchase price of each one one-hundredth share of
AmerisourceBergen Series A preferred stock. For example, if we assume that the
initial purchase price of $275 is in effect on the date that the flip-in
feature of the AmerisourceBergen rights is triggered, any holder of an
AmerisourceBergen right, except for the person that has become the beneficial
owner of 15% or more of the AmerisourceBergen common stock then outstanding,
may exercise his or her AmerisourceBergen right by paying to AmerisourceBergen
$275 in order to receive from AmerisourceBergen shares of AmerisourceBergen
Series A preferred stock having a value equal to $550.

  "Flip Over" Feature. In the event that following a public announcement a
person has become the beneficial owner of 15% or more of the AmerisourceBergen
common stock then outstanding:

  .  AmerisourceBergen merges into another entity,

  .  another entity merges into AmerisourceBergen, or

  .  AmerisourceBergen sells more than 50% of its assets or earning power,

then each holder of an AmerisourceBergen right, except for such person that is
the beneficial owner of 15% or more of the AmerisourceBergen common stock then
outstanding, may have the right to receive, upon exercise of

                                      38


the AmerisourceBergen right, the number of shares of the acquiring company's
capital stock with the greatest voting power having a value equal to twice the
then current purchase price of each one one-hundredth share of
AmerisourceBergen Series A preferred stock.

  "Exchange" Feature. At any time after a person becomes the beneficial owner
of 15% or more, but, in certain circumstances, less than 50%, of the
AmerisourceBergen common stock then outstanding, the board of directors of
AmerisourceBergen may, at its option, exchange all or part of the
AmerisourceBergen rights, except for those held by such acquiring person, for
AmerisourceBergen common stock at an exchange ratio of one one-hundredth of a
share of AmerisourceBergen common stock for each AmerisourceBergen right,
subject to adjustment, and cash instead of fractional shares, if any. Use of
this exchange feature means that eligible AmerisourceBergen rights holders
will not have to pay a purchase price before receiving shares of
AmerisourceBergen Series A preferred stock.

  Redemption of Rights. At any time prior to the earlier to occur of:

  .  10 business days following a public announcement that a person has
     become the beneficial owner of 15% or more of the AmerisourceBergen
     common stock then outstanding, or

  .  August 27, 2011


the board of directors of AmerisourceBergen may redeem all of the
AmerisourceBergen rights at a redemption price of $0.01 per right, subject to
adjustment. The right to exercise the AmerisourceBergen rights will terminate
upon redemption, and at that time, the holders of the AmerisourceBergen rights
will have the right to receive only the redemption price for each
AmerisourceBergen right they hold.

  Amendment of Rights. At any time prior to the earlier to occur of:

  .  10 business days following a public announcement that a person has
     become the beneficial owner of 15% or more of the AmerisourceBergen
     common stock then outstanding; and


  .  10 business days, or such later date as may be determined by the board
     of directors of AmerisourceBergen, following the commencement of a
     tender offer or exchange offer that would result in a person becoming
     the beneficial owner of 15% or more of the AmerisourceBergen common
     stock then outstanding,


the terms of the existing AmerisourceBergen rights agreement may be amended by
the board of directors of AmerisourceBergen without the approval of the
holders of the rights. However, after the earlier to occur of (a) and (b)
above, the rights agreement may not be amended in any manner that would
adversely affect the interests of the holders of the AmerisourceBergen rights,
excluding the interests of the acquiror.

  Termination of Rights. If not previously exercised, the AmerisourceBergen
rights will expire on August 27, 2011 unless AmerisourceBergen earlier redeems
or exchanges the AmerisourceBergen rights or extends the expiration date as
provided in the rights agreement.


  Anti-Takeover Effects. The AmerisourceBergen rights have anti-takeover
effects. Once the AmerisourceBergen rights have become exercisable, in most
cases the AmerisourceBergen rights will cause substantial dilution to a person
that attempts to acquire or merge with AmerisourceBergen. Accordingly, the
existence of the AmerisourceBergen rights may deter potential acquirors from
making a takeover proposal or a tender offer. The AmerisourceBergen rights
should not interfere with any merger or other business combination approved by
the board of directors of AmerisourceBergen since AmerisourceBergen may redeem
the AmerisourceBergen rights.

                                      39


                            SELLING SECURITYHOLDERS

  AmeriSource originally issued the notes in a private placement in December,
2000. The initial purchasers of the notes have advised AmeriSource that the
notes were resold in transactions exempt from the registration requirements of
the Securities Act to "qualified institutional buyers", as defined in Rule
144A of the Securities Act. These subsequent purchasers, or their transferees,
pledgees, donees or successors, may from time to time offer and sell any or
all of the notes and/or shares of the common stock issuable upon conversion of
the notes pursuant to this prospectus.

  The notes and the shares of common stock issuable upon conversion of the
notes have been registered in accordance with the registration rights
agreement. Pursuant to the registration rights agreement, AmeriSource is
required to file a registration statement with regard to the notes and the
shares of AmerisourceBergen common stock issuable upon conversion of the notes
and to keep the registration statement effective until the earlier of:


    (1) the sale of all the securities registered under the registration
  rights agreement;

    (2) the expiration of the holding period applicable to these securities
  under Rule 144(k) under the Securities Act with respect to persons who are
  not our affiliates; and

    (3) two years from the date the notes were originally issued.

  The selling securityholders may choose to sell notes and/or the shares of
common stock issuable upon conversion of the notes from time to time. See
"Plan of Distribution".

  The following table sets forth:

    (1) the name of each selling securityholder who has provided us with
  notice as of the date of this prospectus pursuant to the registration
  rights agreement of their intent to sell or otherwise dispose of notes
  and/or shares of common stock issuable upon conversion of the notes
  pursuant to the registration statement,


    (2) the principal amount of notes and the number of shares of
  AmerisourceBergen common stock issuable upon conversion of the notes which
  they may sell from time to time pursuant to the registration statement, and

    (3) the amount of outstanding notes and AmerisourceBergen common stock
  beneficially owned by the selling securityholder prior to the offering,
  assuming no conversion of the notes.

  To our knowledge, no selling securityholder nor any of its affiliates has
held any position or office with, been employed by or otherwise has had any
material relationship with us or our affiliates during the three years prior
to the date of this prospectus.

  A selling securityholder may offer all or some portion of the notes and
shares of the common stock issuable upon conversion of the notes. Accordingly,
no estimate can be given as to the amount or percentage of notes or our common
stock that will be held by the selling securityholders upon termination of
sales pursuant to this prospectus. In addition, the selling securityholders
identified below may have sold, transferred or disposed of all or a portion of
their notes since the date on which they provided the information regarding
their holdings in transactions exempt from the registration requirements of
the Securities Act.

  The information contained under the column heading "Shares That May be Sold"
assumes conversion of the full amount of the notes held by the holder at the
initial rate of 18.8791 shares of common stock per each $1,000 principal
amount of notes.

                                      40





                                                             Shares of
                                                              Common
                                      Amount of                Stock   Shares
                                     Notes Owned  Amount of    Owned    That
                                       Before    Notes that   Before   May be
                Name                  Offering   May be Sold Offering   Sold
                                                           
AAM Zazove Institutional Income
 Fund, L.P.......................... $   900,000 $   900,000      0     16,991
Aftra Health Fund................... $   600,000 $   600,000      0     11,327
AIG/National Union Fire Insurance... $   300,000 $   300,000      0      5,664
Alpine Associates................... $ 2,850,000 $ 2,850,000      0     53,805
Alpine Partners, L.P................ $   550,000 $   550,000      0     10,384
American Motorist Insurance
 Company............................ $   462,000 $   462,000      0      8,722
American Samoa Government........... $    40,000 $    40,000      0        755
AmSouth Bank, custodian for AmSouth
 Equity Income Fund................. $ 2,890,000 $ 2,890,000      0     54,561
AmSouth Bank, custodian for AmSouth
 Variable Equity Income Fund........ $ 1,570,000 $ 1,570,000      0     29,640
Arapahoe County Colorado............ $    44,000 $    44,000      0        831
Arbitex Master Fund, L.P............ $ 2,000,000 $ 2,000,000      0     37,758
Arkansas PERS....................... $   990,000 $   990,000      0     18,690
Associated Electric & Gas Insurance
 Services Limited................... $   500,000 $   500,000      0      9,440
Aventis Pension Master Trust........ $   110,000 $   110,000      0      2,077
Banc of America Securities L.L.C.
 (1)................................ $    35,000 $    35,000      0        661
Bancroft Convertible Fund, Inc...... $ 1,000,000 $ 1,000,000      0     18,879
Bank Austria Cayman Islands, Ltd.... $ 9,330,000 $ 9,330,000      0    176,142
BBT Fund, L.P....................... $10,000,000 $10,000,000      0    188,791
Bear, Stearns & Company, Inc........ $ 2,500,000 $ 2,500,000      0     47,198
Bear, Stearns Securities Corp....... $ 4,000,000 $ 4,000,000      0     75,516
Boilermaker-Blacksmith Pension
 Trust.............................. $   685,000 $   685,000      0     12,932
Boilermakers Blacksmith Pension
 Trust.............................. $ 1,380,000 $ 1,380,000      0     26,053
BP Amoco Corporation Master Trust
 for Employee Pension Plans......... $ 8,240,000 $ 8,240,000      0    155,564
BP Amoco PLC Master Trust........... $ 1,669,000 $ 1,669,000      0     31,509
British Virgin Island Social
 Security Board..................... $    33,000 $    33,000      0        623
BS Debt Income Fund-Class A......... $    10,000 $    10,000      0        189
BT Opportunity...................... $ 4,000,000 $ 4,000,000      0     75,516
BT Strategy......................... $ 1,000,000 $ 1,000,000      0     18,879
Calamos Convertible Fund-Calamos
 Investment Trust................... $ 2,430,000 $ 2,430,000      0     45,876
Calamos Convertible Growth and
 Income Fund- Calamos Investment
 Trust.............................. $ 1,520,000 $ 1,520,000      0     28,696
Calamos Convertible Portfolio-
 Calamos Advisors Trust............. $   100,000 $   100,000      0      1,888
Calamos Global Convertible Fund-
 Calamos Investment Trust........... $   305,000 $   305,000      0      5,758
Castle Convertible Fund, Inc........ $   500,000 $   500,000      0      9,440
Chrysler Corporation Master
 Retirement Trust................... $ 3,110,000 $ 3,110,000      0     58,714
Citi Cap Arb Fund................... $   689,000 $   689,000      0     13,008
City of Albany Pension Plan......... $    65,000 $    65,000      0      1,227
City of Knoxville Pension System.... $   150,000 $   150,000      0      2,832
City of New Orleans................. $   172,000 $   172,000      0      3,247
City University of New York......... $   112,000 $   112,000      0      2,114
Clarica Life Insurance Co.-U.S...... $   275,000 $   275,000      0      5,192
Continental Assurance Company....... $ 2,480,000 $ 2,480,000      0     46,820
Continental Assurance Company on
 behalf of ITS...................... $ 3,480,000 $ 3,480,000      0     65,699
Convertible Arb Qib................. $ 1,300,000 $ 1,300,000      0     24,543



                                       41





                                                              Shares of
                                                               Common
                                       Amount of                Stock   Shares
                                      Notes Owned  Amount of    Owned    That
                                        Before    Notes that   Before   May be
                Name                   Offering   May be Sold Offering   Sold
                                                            
De Am Convertible Arbitrage Fund....  $ 5,250,000 $ 5,250,000      0     99,115
Delaware PERS.......................  $ 1,525,000 $ 1,525,000      0     28,791
Delta Air Lines Master Trust........  $ 1,285,000 $ 1,285,000      0     24,260
Delta Air Lines Master Trust........  $ 1,275,000 $ 1,275,000      0     24,071
Delta Pilots D & S Trust............  $   215,000 $   215,000      0      4,059
Delta Pilots Disability and
 Survivorship Trust.................  $   375,000 $   375,000      0      7,080
Diversified Arb Fund................  $ 2,425,000 $ 2,425,000      0     45,782
Drury University....................  $    40,000 $    40,000      0        755
Ellsworth Convertible Growth and
 Income Fund........................  $ 1,000,000 $ 1,000,000      0     18,679
Employee Benefit Convertible
 Securities Fund....................  $   180,000 $   180,000      0      3,398
Enron North America, Corp...........  $ 2,000,000 $ 2,000,000      0     37,758
F.R. Convertible Securities Fund....  $    80,000 $    80,000      0      1,510
Family Service Life Insurance
 Company............................  $   100,000 $   100,000      0      1,888
Federated Equity Income Fund, Inc...  $31,470,000 $31,470,000      0    594,125
Federated Insurance Series on behalf
 of Federated Equity Income Fund
 II.................................  $ 1,200,000 $ 1,200,000      0     22,655
Fidelity Financial Trust: Fidelity
 Convertible Securities Fund........  $ 4,300,000 $ 4,300,000      0     81,180
General Motors Investment Management
 Corp...............................  $ 4,000,000 $ 4,000,000      0     75,516
General Motors Welfare Benefit Trust
 Arb Fund...........................  $   375,000 $   375,000      0      7,080
Goldman, Sachs & Company(1)(2)......  $12,450,000 $12,450,000      0    235,045
Grady Hospital Foundation...........  $    99,000 $    99,000      0      1,869
Greek Catholic Union................  $    20,000 $    20,000      0        378
Greek Catholic Union II.............  $    15,000 $    15,000      0        283
Guardian Life Insurance Company of
 America............................  $ 4,700,000 $ 4,700,000      0     88,732
Guardian Pension Trust..............  $   200,000 $   200,000      0      3,776
H.K. Porter Company, Inc............  $    20,000 $    20,000      0        378
HFR Convertible Arbitrage Account...  $   200,000 $   200,000      0      3,776
Hotel Union and Hotel Industry of
 Hawaii.............................  $   339,000 $   339,000      0      6,400
ICI American Holdings...............  $   825,000 $   825,000      0     15,575
Independence Blue Cross.............  $   120,000 $   120,000      0      2,265
Island Holdings.....................  $    15,000 $    15,000      0        283
Jefferies & Company Inc.............  $   200,000 $   200,000      0      3,776
Jefferies & Company Inc.............  $     7,000 $     7,000      0        132
KBC Financial Products USA..........  $   500,000 $   500,000      0      9,440
Kemper Foundation...................  $   100,000 $   100,000      0      1,888
Kentfield Trading, Ltd..............  $11,070,000 $11,070,000      0    208,992
Kettering Medical Center Funded
 Depreciation Account...............  $    45,000 $    45,000      0        850
Knoxville Utilities Board Retirement
 System.............................  $   100,000 $   100,000      0      1,888
Lancer Securities Cayman Ltd........  $   250,000 $   250,000      0      4,720
Lehman Brothers, Inc................  $    70,000 $    70,000      0      1,322
Lincoln National Convertible
 Securities Fund....................  $ 1,600,000 $ 1,600,000      0     30,207
Lipper Convertible Series II, L.P...  $ 2,000,000 $ 2,000,000      0     37,758
Lipper Convertibles, L.P............  $ 8,850,000 $ 8,850,000      0    167,080
Lipper Convertibles, L.P. (Class
 B).................................  $   581,000 $   581,000      0     10,969
Lipper Offshore Convertibles, L.P...  $ 3,000,000 $ 3,000,000      0     56,637
Lipper Offshore Convertibles, L.P.
 #2.................................  $   419,000 $   419,000      0      7,910
Local Initiatives Support
 Corporation........................  $    53,000 $    53,000      0      1,001
Louisiana Workers' Compensation
 Corp...............................  $   100,000 $   100,000      0      1,888
Lumbermens..........................  $   750,000 $   750,000      0     14,159



                                       42





                                                              Shares of
                                        Amount of              Common
                                          Notes    Amount of    Stock   Shares
                                          Owned    Notes that   Owned    That
                                          Before     May be    Before   May be
                 Name                    Offering     Sold    Offering   Sold
                                                            
Mainstay Convertible Fund.............  $8,795,000 $8,795,000      0    166,042
Mainstay VP Convertible Portfolio.....  $2,250,000 $2,250,000      0     42,478
Market Neutral Arb Fund...............  $1,002,000 $1,002,000      0     18,917
McMahan Securities Co. L.P............  $1,020,000 $1,020,000      0     19,257
Merrill Lynch Insurance Group(3)......  $   98,000 $   98,000      0      1,850
Miller Tabak Roberts Securities, LLC..  $  170,000 $  170,000      0      3,209
Morgan Stanley & Co...................  $1,528,000 $1,528,000      0     28,847
Motion Picture Industry Health Plan-
 Active Member Fund...................  $  435,000 $  435,000      0      8,212
Motion Picture Industry Health Plan-
 Retiree Member Fund..................  $  145,000 $  145,000      0      2,737
Municipal Employees...................  $  140,000 $  140,000      0      2,643
Muni Strategy Arbitrage...............  $4,447,000 $4,447,000      0     83,955
Nabisco Holdings......................  $   41,000 $   41,000      0        774
Nalco Chemical Company................  $  100,000 $  100,000      0      1,888
Nations Convertible Securities Fund...  $4,745,000 $4,745,000      0     89,581
Nationwide Separate Account Trust on
 behalf of Nationwide Equity Income
 Fund.................................  $  640,000 $  640,000      0     12,083
New Orleans Firefighters
 Pension/Relief Fund..................  $  144,000 $  144,000      0      2,719
New York Life Insurance Company.......  $7,200,000 $7,200,000      0    135,930
New York Life Insurance Company and
 Annuity Corporation..................  $  800,000 $  800,000      0     15,103
New York Life Separate Account #7.....  $1,200,000 $1,200,000      0     22,655
1976 Distribution Trust FBO Jane A.
 Lauder...............................  $   17,000 $   17,000      0        321
1976 Distribution Trust FBO
 Lauder/Zinterhofer...................  $   18,000 $   18,000      0        340
Occidental Petroleum Corporation......  $  178,000 $  178,000      0      3,360
OCM Convertible Trust.................  $1,845,000 $1,845,000      0     34,832
Ohio Bureau of Workers Compensation...  $  150,000 $  150,000      0      2,832
Ohio National Fund, Inc. on behalf of
 Equity Income Portfolio..............  $  120,000 $  120,000      0      2,265
Pacific Life Insurance Company........  $  500,000 $  500,000      0      9,440
Palladin Securities L.L.C.............  $  500,000 $  500,000      0      9,440
Partner Reinsurance Company Ltd.......  $  750,000 $  750,000      0     14,159
PGEP IV...............................  $   80,000 $   80,000      0      1,510
Policemen and Firemen Retirement
 System of the City of Detroit........  $  500,000 $  500,000      0      9,440
Port Authority of Allegheny County
 Retirement and Disability Allowance
 Plan for the Employees represented by
 Local 85 of the Amalgamated Transit
 Union................................  $  725,000 $  725,000      0     13,687
Primerica Life Insurance Company......  $  869,000 $  869,000      0     16,406
Pro Mutual............................  $  560,000 $  560,000      0     10,572
Ramius Capital Group Holdings, Ltd....  $  600,000 $  600,000      0     11,327
Ramius Capital Group Latitude Master
 Fund.................................  $1,500,000 $1,500,000      0     28,319
Raytheon Master Pension Trust.........  $  506,000 $  506,000      0      9,553
Regence Oregon........................  $  166,000 $  166,000      0      3,134
Regence Utah..........................  $   56,000 $   56,000      0      1,057
Regence Washington....................  $  278,000 $  278,000      0      5,248



                                       43





                                                            Shares of
                                                             Common
                                     Amount of                Stock     Shares
                                    Notes Owned  Amount of    Owned      That
                                      Before    Notes that   Before     May be
               Name                  Offering   May be Sold Offering     Sold
                                                            
RJR Reynolds......................  $    86,000 $    86,000        0      1,624
Rockhaven Fund....................  $    80,000 $    80,000        0      1,510
Rockhaven Premier Dividend Fund...  $   690,000 $   690,000        0     13,027
SB Convertible Fund...............  $ 1,000,000 $ 1,000,000        0     18,879
SCI Endowment Care Common Trust
 Fund-National Fiduciary
 Services.........................  $    55,000 $    55,000        0      1,038
SCI Endowment Care Common Trust
 Fund-Suntrust....................  $    85,000 $    85,000        0      1,605
SG Cowen Securities, Inc..........  $ 2,040,000 $ 2,040,000        0     38,513
Shell Pension Trust...............  $   393,000 $   393,000        0      7,419
SPT...............................  $   570,000 $   570,000        0     10,761
Starvest Combined Portfolio.......  $   310,000 $   310,000        0      5,853
State Employees' Retirement Fund
 of the State of Delaware.........  $ 1,570,000 $ 1,570,000        0     29,640
State of Connecticut Combined
 Investment Funds.................  $ 4,120,000 $ 4,120,000        0     77,782
State of Maryland Retirement
 System...........................  $ 2,358,000 $ 2,358,000        0     44,517
State of Oregon/Equity............  $ 4,950,000 $ 4,950,000        0     93,452
The Class 1C Company..............  $ 2,000,000 $ 2,000,000        0     37,758
The Dow Chemical Company
 Employees' Retirement Plan.......  $ 1,400,000 $ 1,400,000        0     26,431
The Estate of James Campbell......  $   285,000 $   285,000        0      5,381
The Fondren Foundation............  $    50,000 $    50,000        0        944
The Grable Foundation.............  $    86,000 $    86,000        0      1,624
The Travelers Indemnity Company...  $ 2,565,000 $ 2,565,000        0     48,425
The Travelers Insurance Company...  $   166,000 $   166,000        0      3,134
The Travelers Insurance Company-
 Life.............................  $ 1,474,000 $ 1,474,000        0     27,828
The Travelers Insurance Company
 Separate Account TLAC............  $   166,000 $   166,000        0      3,134
The Travelers Life and Annuity
 Company..........................  $   176,000 $   176,000        0      3,323
Travelers Series Managed Assets
 Trust............................  $    75,000 $    75,000        0      1,416
Travelers Series Trust Convertible
 Bond Portfolio...................  $   225,000 $   225,000        0      4,248
UBKAM Arbitrage Fund Ltd..........  $ 1,500,000 $ 1,500,000        0     28,319
UBKAM Global High Yield Fund
 Ltd..............................  $ 1,500,000 $ 1,500,000        0     28,319
UBS O'Connor, LLC F/B/O Global
 Equity...........................  $ 4,000,000 $ 4,000,000        0     75,516
UBS Warburg, LLC..................  $ 6,800,000 $ 6,800,000        0    128,378
Unifi, Inc. Profit Sharing Plan
 and Trust........................  $    70,000 $    70,000        0      1,322
United Food and Commercial Workers
 Local 1262 and Employers Pension
 Fund ............................  $   330,000 $   330,000        0      6,230
United Healthcare Insurance
 Company..........................  $   450,000 $   450,000        0      8,496
Value Line Convertible Fund,
 Inc..............................  $   500,000 $   500,000        0      9,440
Van Kampen Harbor Fund............  $ 4,000,000 $ 4,000,000  628,000(4)  75,516
Vanguard Convertible Securities
 Fund, Inc........................  $ 4,450,000 $ 4,450,000        0     84,012
Vopak USA, Inc. Retirement Plan...  $   195,000 $   195,000        0      3,681
Zeneca AG Products, Inc...........  $   150,000 $   150,000        0      2,832
Zeneca Holdings Trust.............  $   375,000 $   375,000        0      7,080
Zurich HFR Master Hedge Fund Index
 Ltd..............................  $    80,000 $    80,000        0      1,510
Zurich Institutional Benchmarks
 Master Fund Ltd. (Global)........  $ 1,100,000 $ 1,100,000        0     20,767
Unknown (5).......................  $17,810,000 $17,810,000      --     336,237



                                       44


---------------------
(1)  One of the initial purchasers.
(2)  Goldman, Sachs & Company acted as financial advisor to AmeriSource in its
     merger transaction with Bergen.
(3)  Merrill Lynch, Pierce, Fenner & Smith Incorporated acted as financial
     advisor to Bergen in its merger transaction with AmeriSource.
(4)  All of these shares of common stock are held by entities affiliated with
     the Van Kampen Harbor Fund.
(5)  The name "Unknown" represents the remaining selling securityholders. We
     are unable to provide the names of these securityholders because certain
     of these notes are currently evidenced by a global note which has been
     deposited with DTC and registered in the name of CEDE & Co. as DTC's
     nominee.

  If, after the date of this prospectus, a securityholder notifies us pursuant
to the registration rights agreement of its intent to dispose of notes
pursuant to the registration statement, we may supplement this prospectus to
include that information.

                             PLAN OF DISTRIBUTION

  We are registering the notes and the shares of our common stock issuable
upon conversion of the notes to permit public secondary trading of these
securities by the holders from time to time after the date of this prospectus.
We have agreed, among other things, to bear all expenses, other than
underwriting discounts and selling commissions, in connection with the
registration and sale of the notes and the shares of common stock issuable
upon conversion of the notes covered by this prospectus.


  We will not receive any of the proceeds from the offering of the notes or
the shares of AmerisourceBergen common stock issuable upon conversion of the
notes by the selling securityholders. The notes and shares of common stock
issuable upon conversion of the notes may be sold from time to time directly
by any selling securityholder or, alternatively, through underwriters, broker-
dealers or agents. If notes or shares of common stock issuable upon conversion
of the notes are sold through underwriters or broker-dealers, the selling
securityholder will be responsible for underwriting discounts or commissions
or agents' commissions.

  The notes or shares of common stock issuable upon conversion of the notes
may be sold:

  .  in one or more transactions at fixed prices,

  .  at prevailing market prices at the time of sale,

  .  at varying prices determined at the time of sale, or


  .  at negotiated prices.

  These sales may be effected in transactions, which may involve block trades
or transactions in which the broker acts as agent for the seller and the
buyer:

  .  on any national securities exchange or quotation service on which the
     notes or shares of common stock issuable upon conversion of the notes
     may be listed or quoted at the time of sale,

  .  in the over-the-counter market,

  .  in transactions otherwise than on a national securities exchange or
     quotation service or in the over-the-counter market or through the
     writing of options.

  In connection with sales of the notes or shares of common stock issuable
upon conversion of the notes or otherwise, any selling securityholder may:

  .  enter into hedging transactions with broker-dealers, which may in turn
     engage in short sales of the notes or shares of common stock issuable
     upon conversion of the notes in the course of hedging the positions they
     assume,

                                      45



  .  sell short and deliver notes or shares of common stock issuable upon
     conversion of the notes to close out the short positions, or


  .  loan or pledge notes or shares of common stock issuable upon conversion
     of the notes to broker-dealers that in turn may sell the securities.

  The outstanding AmerisourceBergen common stock is publicly traded on the New
York Stock Exchange. The initial purchasers of the notes have advised us that
certain of the initial purchasers are making and currently intend to continue
making a market in the notes; however, they are not obligated to do so and any
market-making of this type may be discontinued at any time without notice, in
the sole discretion of the initial purchasers. We do not intend to apply for
listing of the notes on the New York Stock Exchange or any securities
exchange. Accordingly, we cannot assure that any trading market will develop
or have any liquidity.

  The selling securityholders and any broker-dealers, agents or underwriters
that participate with the selling securityholders in the distribution of the
notes or the shares of common stock issuable upon conversion of the notes may
be deemed to be "underwriters" within the meaning of the Securities Act, in
which event any commissions received by these broker-dealers, agents or
underwriters and any profits realized by the selling securityholders on the
resales of the notes or the shares may be deemed to be underwriting
commissions or discounts under the Securities Act.

  In addition, any securities covered by this prospectus which qualify for
sale pursuant to Rule 144, Rule 144A or any other available exemption from
registration under the Securities Act may be sold under Rule 144, Rule 144A or
any of the other available exemptions rather than pursuant to this prospectus.

  There is no assurance that any selling securityholder will sell any or all
of the notes or shares of common stock issuable upon conversion of the notes
described in this prospectus, and any selling securityholder may transfer,
devise or gift the securities by other means not described in this prospectus.

  AmeriSource originally sold the notes to the initial purchasers in December
2000 in a private placement. AmeriSource agreed to indemnify and hold the
initial purchasers of the notes harmless against certain liabilities under the
Securities Act that could arise in connection with the sale of the notes by
the initial purchasers. The registration rights agreement provides for
AmeriSource and the selling securityholders to indemnify each other against
certain liabilities arising under the Securities Act.

  AmeriSource agreed pursuant to the registration rights agreement to use
reasonable efforts to cause the registration statement to which this
prospectus relates to become effective within 180 days after the date the
notes were originally issued and to keep the registration statement effective
until the earlier of:

  .  the sale of all the securities registered under the registration rights
     agreement,

  .  the expiration of the holding period applicable to the securities under
     Rule 144(k) under the Securities Act with respect to persons who are not
     AmeriSource's affiliates, and

  .  two years from the date the notes were originally issued.

  The registration rights agreement provides that AmeriSource may suspend the
use of this prospectus in connection with sales of notes and shares of common
stock issuable upon conversion of the notes by holders for a period not to
exceed an aggregate of 45 days in any 90-day period or 90 days in any 12-month
period if any event occurs or any fact exists that would render the
registration statement materially misleading. AmerisourceBergen and
AmeriSource will bear the expenses of preparing and filing the registration
statement and all post-effective amendments.

                                 LEGAL MATTERS

  The validity of the notes and the shares of common stock issuable upon
conversion of the notes offered hereby will be passed upon for AmeriSource and
AmerisourceBergen by Dechert, 4000 Bell Atlantic Tower, 1717 Arch Street,
Philadelphia, Pennsylvania 19103.


                                      46


                                    EXPERTS

  AmerisourceBergen Corporation. Ernst & Young LLP, independent auditors, have
audited the consolidated balance sheet of AmerisourceBergen Corporation as of
March 31, 2001, as set forth in their report which is incorporated by
reference in this prospectus and elsewhere in this registration statement.
AmerisourceBergen's consolidated balance sheet is incorporated by reference in
reliance on Ernst & Young LLP's report, given on their authority as experts in
accounting and auditing.

  AmerisourceBergen Corporation. The consolidated balance sheet of
AmerisourceBergen Corporation as of March 31, 2001, which is incorporated in
this prospectus by reference from Form S-4, has been audited by Deloitte &
Touche LLP, independent auditors, as stated in their report, which is
incorporated herein by reference, and has been so incorporated in reliance
upon the report of such firm given upon their authority as experts in
accounting and auditing.

  AmeriSource. Ernst & Young LLP, independent auditors, have audited the
consolidated financial statements and schedules of AmeriSource Health
Corporation included in AmeriSource's Annual Report on Form 10-K for the year
ended September 30, 2000, as set forth in their report, which is incorporated
by reference in this prospectus. AmeriSource's consolidated financial
statements and schedules are incorporated by reference in reliance on Ernst &
Young LLP's report, given on their authority as experts in accounting and
auditing.

  Bergen. The consolidated financial statements and the related financial
statement schedules incorporated in this prospectus by reference from Bergen
Brunswig Corporation's Annual Report on Form 10-K for the year ended September
30, 2000 have been audited by Deloitte & Touche LLP, independent auditors, as
stated in their reports, which are incorporated herein by reference, and have
been so incorporated in reliance upon the reports of such firm given upon
their authority as experts in accounting and auditing.


                                      47


                                    PART II

                    INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses Of Issuance And Distribution.

  The following table sets forth an estimate of the expenses that will be
incurred by AmerisourceBergen in connection with the sale and distribution of
the common stock being registered in this registration statement.


                                                                  
     Securities and Exchange Commission registration fee............        0(1)
     Printing and engraving expenses................................ $ 25,000
     Legal fees and expenses........................................ $ 50,000
     Accounting fees and expenses................................... $ 25,000
     Miscellaneous.................................................. $ 10,000
                                                                     --------
       Total........................................................ $110,000
                                                                     ========

---------------------
(1)   Previously paid pursuant to Rule 429 of the Securities Act.

Item 15. Indemnification of Directors and Officers.

  Delaware law provides that a corporation may include in its certificate of
incorporation a provision limiting or eliminating the liability of its
directors to the corporation and its stockholders for monetary damages arising
from a breach of fiduciary duty, except for:

  .   a breach of the duty of loyalty to the corporation or its stockholders;

  .   acts or omissions not in good faith or which involve intentional
      misconduct or a knowing violation of law;

  .   payment of a dividend or the repurchase or redemption of stock in
      violation of Delaware law; or

  .   any transaction from which the director derived an improper personal
      benefit.

  The certificate of incorporation of each of the Registrants provides that
the directors are entitled to the benefits of all limitations on the liability
of directors that are now or hereafter become available under Delaware law.
Specifically, no director will be liable to the relevant Registrant or its
stockholders for monetary damages for breach of fiduciary duty as director,
except for liability (a) for any breach of the director's duty of loyalty to
the relevant Registrant or its stockholders, (b) for acts or omissions not in
good faith or which involve intentional misconduct or a knowing violation of
law, (c) under section 174 of the Delaware law, which pertains, among other
things, to liability for the unlawful payment of dividends, or (d) for any
transaction from which the director derived an improper personal benefit.


  Under Delaware law, a corporation may indemnify directors and officers:

  .   for actions taken in good faith and in a manner they reasonably
      believed to be in, or not opposed to, the best interests of the
      corporation; and

  .   with respect to any criminal proceeding, they had no reasonable cause
      to believe that their conduct was unlawful.

  In addition, Delaware law provides that a corporation may advance to a
director or officer expenses incurred in defending any action upon receipt of
an undertaking by the director or officer to repay the amount advanced if it
is ultimately determined that he or she is not entitled to indemnification.

  The certificate of incorporation of each of the Registrants provides that
the relevant Registrant will indemnify any person who is or was a director or
officer of such Registrant, or is or was serving at the request of such
Registrant, as a director, officer or trustee of another corporation, trust or
other enterprise, with respect to


                                     II-1



actions taken or omitted by such person in any capacity in which such person
serves such Registrant or such other corporation, trust or other enterprise,
to the full extent authorized or permitted by law, as now or hereafter in
effect, and such right to indemnification will continue as to a person who has
ceased to be a director, officer or trustee, as the case may be, and will
inure to the benefit of such person's heirs, executors and personal and legal
representatives.


Item 16. Exhibits.

  The following exhibits are filed herewith unless otherwise indicated:



 Exhibit
 Number                                Description
 -------                               -----------
      
  3.1*   Amended and Restated Certificate of Incorporation, as amended, of
         AmerisourceBergen Corporation (incorporated by reference to Exhibit
         3.1 to the Registration Statement on Form S-4 filed on May 23, 2001
         (Registration No. 333-61440)).

  3.2*   Amended and Restated Bylaws of AmerisourceBergen Corporation
         (incorporated by reference to Exhibit 3.2 to the Registration
         Statement on Form S-4 filed on May 23, 2001 (Registration No. 333-
         61440)).

  4.1*   Indenture, dated as of December 12, 2000, among AmeriSource Health
         Corporation, as Issuer, AmeriSource Corporation, as Guarantor, and
         Bank One Trust Company, N.A., as Trustee for the 5% Convertible
         Subordinated Notes due December 15, 2007 (incorporated by reference to
         Exhibit 4.16 to AmeriSource Health Corporation's Quarterly Report on
         Form 10-Q for the quarter ended December 31, 2000).

  4.2*   Registration Rights Agreement, dated December 12, 2000, among
         AmeriSource Health Corporation, as Issuer, AmeriSource Corporation, as
         Guarantor, and the Purchasers for the 5% Convertible Subordinated
         Notes due December 15, 2007 (incorporated by reference to Exhibit 4.18
         to AmeriSource Health Corporation's Quarterly Report on Form 10-Q for
         the quarter ended December 31, 2000).

  4.3*   Form of 5% Convertible Subordinated Note (included in Exhibit 4.1).

  4.4    First Supplemental Indenture dated as of August 29, 2001 among
         AmeriSource Health Corporation, as issuer, AmeriSource Corporation, as
         guarantor, AmerisourceBergen Corporation and Bank One Trust Company,
         N.A., as Trustee.

  5.1    Opinion of Dechert regarding legality of securities being registered.

 12.1*   Computation of Ratio of Earnings to Fixed Charges.

 23.1    Consent of Dechert (included as part of its opinion filed as Exhibit
         5.1 and incorporated herein by reference).

 23.2    Consent of Deloitte & Touche LLP Independent Auditors.

 23.3    Consent of Ernst & Young LLP Independent Auditors.

 24.1    Power of Attorney (included on the signature page of this Form S-3 and
         incorporated herein by reference).

 25.1*   Form T-1 Statement of Eligibility of Trustee for Indenture under the
         Trust Indenture Act of 1939 (incorporated by reference to Exhibit 25.1
         to AmeriSource Health Corporation's Registration Statement on Form S-3
         filed March 2, 2001).

---------------------
*   Previously filed.


                                     II-2


Item 17. Undertakings.

  Each undersigned Registrant hereby undertakes:

  (1) To file, during any period in which offers or sales are being made, a
post-effective amendment to this Registration Statement:

    (a) To include any prospectus required by Section 10(a)(3) of the
  Securities Act of 1933,

    (b) To reflect in the prospectus any facts or events arising after the
  effective date of the registration statement (or the most recent post-
  effective amendment thereof) which, individually or in the aggregate,
  represent a fundamental change in the information set forth in the
  Registration Statement.

    Notwithstanding the foregoing, any increase or decrease in volume of
  securities offered (if the total dollar value of securities offered would
  not exceed that which was registered) and any deviation from the low or
  high end of the estimated maximum offering range may be reflected in the
  form of prospectus filed with the Commission pursuant to Rule 424(b) if, in
  the aggregate, the changes in volume and price represent no more than a 20
  percent change in the maximum aggregate offering price set forth in the
  "Calculation of Registration Fee" table in the effective registration
  statement,

    (c) To include any material information with respect to the plan of
  distribution not previously disclosed in the Registration Statement or any
  material change to such information in the Registration Statement;
  provided, however, that clauses (a) and (b) do not apply if the information
  required to be included in a post-effective amendment by such clauses is
  contained in periodic reports filed with or furnished to the Securities and
  Exchange Commission by the Registrant pursuant to Section 13 or Section
  15(d) of the Securities Exchange Act of 1934 (the "Exchange Act") that are
  incorporated by reference in the Registration Statement.

  (2) That, for the purpose of determining any liability under the Securities
Act, each such post-effective amendment shall be deemed a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

  (3) To remove from registration by means of a post-effective amendment any
of the securities being registered which remain unsold at the termination of
the offering.

  (4) That, for purposes of determining any liability under the Securities
Act, each filing of the Registrant's annual report pursuant to Section 13(a)
or Section 15(d) of the Exchange Act that is incorporated by reference in this
Registration Statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

  Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the provisions described under Item 15 above, or
otherwise, the Registrant has been advised that in the opinion of the
Securities and Exchange Commission such indemnification is against public
policy as expressed in the Securities Act and is, therefore, unenforceable. In
the event that a claim for indemnification against such liabilities, other
than the payment by the Registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of
any action, suit or proceeding, is asserted by such director, officer or
controlling person in connection with the securities being registered, the
Registrant will, unless in the opinion of its counsel the matter has been
settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

  The undersigned registrant hereby undertakes to file an application for the
purpose of determining the eligibility of the trustee to act under subsection
(a) of Section 310 of the Trust Indenture Act in accordance with the rules and
regulations prescribed by the Commission under Section 305(b)(2) of the Act.

                                     II-3


                                  SIGNATURES

  Pursuant to the requirements of the Securities Act, the Registrant certifies
that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-3 and has duly caused this Registration
Statement on Form S-3 to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Chesterbrook, Commonwealth of Pennsylvania, on
September 6, 2001.


                                          AmerisourceBergen Corporation

                                              /s/ William D. Sprague

                                          By: _________________________________
                                             Name: William D. Sprague
                                             Title:  Vice President, General
                                                     Counsel and Secretary

  KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints William D. Sprague or R. David Yost as his/her
attorney-in-fact and agent, with full power of substitution and
resubstitution, for him/her and in his/her name, place, and stead, in any and
all capacities, to sign and file Registration Statement(s) and any and all
pre- or post-effective amendments to such Registration Statement(s), with all
exhibits thereto and hereto, and other documents with the Securities and
Exchange Commission, granting unto said attorney-in-fact and agent, and each
of them, full power and authority to do and perform each and every act and
thing requisite or necessary to be done in and about the premises, as fully to
all intents and purposes as he/she might or could do in person, hereby
ratifying and confirming all that said attorneys-in-fact and agents, or any of
them, or their or his substitutes, may lawfully do or cause to be done by
virtue hereof.


  Pursuant to the requirements of the Securities Act of 1933, as amended, this
prospectus has been signed by the following persons in the capacities and on
the dates indicated.




                 Name                            Title                   Date
                 ----                            -----                   ----

                                                            
                 *                     Chairman                    September 6, 2001
______________________________________
          Robert E. Martini

                 *                     President, Chief Executive  September 6, 2001
______________________________________  Officer and Director
            R. David Yost               (Principal Executive
                                        Officer)

       /s/ Rodney H. Brady             Director                    September 6, 2001
______________________________________
           Rodney H. Brady

       /s/ Richard C. Gozon            Director                    September 6, 2001
______________________________________
           Richard C. Gozon

    /s/ Edward E. Hagenlocker          Director                    September 6, 2001
______________________________________
        Edward E. Hagenlocker

       /s/ James R. Mellor             Director                    September 6, 2001
______________________________________
           James R. Mellor







                  Name                              Title                   Date
                  ----                              -----                   ----

                                                               
       /s/ Francis G. Rodgers             Director                    September 6, 2001
 ______________________________________
           Francis G. Rodgers

       /s/ J. Lawrence Wilson             Director                    September 6, 2001
 ______________________________________
           J. Lawrence Wilson

                   *                      Executive Vice President    September 6, 2001
 ______________________________________    and Chief Financial
             Neil F. Dimick                Officer (Principal
                                           Financial Officer and
                                           Principal Accounting
                                           Officer)

 *By: /s/ William D. Sprague
    ___________________________________
           William D. Sprague
            Attorney-in-fact





  Pursuant to the requirements of the Securities Act, the Registrant certifies
that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-3 and has duly caused this Registration
Statement on Form S-3 to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Chesterbrook, Commonwealth of Pennsylvania, on
September 6, 2001.


                                          AmeriSource Health Corporation


                                          AmeriSource Corporation


                                              /s/ William D. Sprague

                                          By: _________________________________

                                             Name: William D. Sprague

                                             Title:  Vice President, General
                                                     Counsel and Secretary

  KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints William D. Sprague or R. David Yost as his/her
attorney-in-fact and agent, with full power of substitution and
resubstitution, for him/her and in his/her name, place, and stead, in any and
all capacities, to sign and file Registration Statement(s) and any and all
pre- or post-effective amendments to such Registration Statement(s), with all
exhibits thereto and hereto, and other documents with the Securities and
Exchange Commission, granting unto said attorneys-in-fact and agent, and each
of them, full power and authority to do and perform each and every act and
thing requisite or necessary to be done in and about the premises, as fully to
all intents and purposes as he/she might or could do in person, hereby
ratifying and confirming all that said attorneys-in-fact and agents, or any of
them, or their or his substitutes, may lawfully do or cause to be done by
virtue hereof.

  Pursuant to the requirements of the Securities Act of 1933, as amended, this
prospectus has been signed by the following persons in the capacities and on
the dates indicated.




                  Name                              Title                   Date
                  ----                              -----                   ----

                                                               
        /s/ Robert E. Martini             Chairman                    September 6, 2001
 ______________________________________
            Robert E. Martini

                   *                      Chief Executive Officer     September 6, 2001
 ______________________________________    and Director (Principal
              R. David Yost                Executive Officer)

                                          Director                    September 6, 2001
 ______________________________________
             Neil F. Dimick


        /s/ Kurt J. Hilzinger             President, Chief Operating  September 6, 2001
 ______________________________________    Officer and Director
            Kurt J. Hilzinger

                   *                      Vice President and Chief    September 6, 2001
 ______________________________________    Financial Officer
          George L. James, III             (Principal Financial
                                           Officer)

                   *                      Vice President, Controller  September 6, 2001
 ______________________________________    (Principal Accounting
          Michael D. DiCandilo             Officer)

 *By:  /s/ William D. Sprague
    ___________________________________
           William D. Sprague
            Attorney-in-fact




                                 EXHIBIT INDEX




 Exhibit
 Number                                Description
 -------                               -----------
      
  3.1*   Amended and Restated Certificate of Incorporation, as amended, of
         AmerisourceBergen Corporation (incorporated by reference to Exhibit
         3.1 to the Registration Statement on Form S-4 filed on May 23, 2001
         (Registration No. 333-61440)).

  3.2*   Amended and Restated Bylaws of AmerisourceBergen Corporation
         (incorporated by reference to Exhibit 3.2 to the Registration
         Statement on Form S-4 filed on May 23, 2001 (Registration No.
         333-61440)).

  4.1*   Indenture, dated as of December 12, 2000, among AmeriSource Health
         Corporation, as Issuer, AmeriSource Corporation, as Guarantor, and
         Bank One Trust Company, N.A., as Trustee for the 5% Convertible
         Subordinated Notes due December 15, 2007 (incorporated by reference to
         Exhibit 4.16 to AmeriSource Health Corporation's Quarterly Report on
         Form 10-Q for the quarter ended December 31, 2000).

  4.2*   Registration Rights Agreement, dated December 12, 2000, among
         AmeriSource Health Corporation, as Issuer, AmeriSource Corporation, as
         Guarantor, and the Purchasers for the 5% Convertible Subordinated
         Notes due December 15, 2007 (incorporated by reference to Exhibit 4.18
         to AmeriSource Health Corporation's Quarterly Report on Form 10-Q for
         the quarter ended December 31, 2000).

  4.3*   Form of 5% Convertible Subordinated Note (included in Exhibit 4.1).

  4.4    First Supplemental Indenture dated as of August 29, 2001 among
         AmeriSource Health Corporation, as issuer, AmeriSource Corporation, as
         guarantor, AmerisourceBergen Corporation and Bank One Trust Company,
         N.A., as Trustee.

  5.1    Opinion of Dechert regarding legality of securities being registered.

 12.1*   Computation of Ratio of Earnings to Fixed Charges.

 23.1    Consent of Dechert (included as part of its opinion filed as Exhibit
         5.1 and incorporated herein by reference).

 23.2    Consent of Deloitte & Touche LLP Independent Auditors.

 23.3    Consent of Ernst & Young LLP Independent Auditors.

 24.1    Power of Attorney (included on the signature page of this Form S-3 and
         incorporated herein by reference).

 25.1*   Form T-1 Statement of Eligibility of Trustee for Indenture under the
         Trust Indenture Act of 1939 (incorporated by reference to Exhibit 25.1
         to AmeriSource Health Corporation's Registration Statement on Form S-3
         filed March 2, 2001).


---------------------
*   Previously filed.