SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                   FORM 12b-25

                         Commission File Number: 1-10709

                           NOTIFICATION OF LATE FILING


(Check One):  [ ] Form 10-K   [ ] Form 20-F   [X] Form 11-K   [ ] Form 10-Q   
              [ ] Form N-SAR   [ ] Form N-CSR

For Period Ended: December 31, 2004

[ ]  Transition  Report  on Form  10-K [ ]  Transition  Report  on Form 10-Q 
[ ]  Transition  Report  on  Form  20-F [ ]  Transition  Report  on  Form  N-SAR
[ ]  Transition Report on Form 11-K

For the Transition Period Ended: ______________.

Nothing in this form shall be construed to imply that the Commission has
verified any information contained herein.

If the notification relates to a portion of the filing checked above, identify
the item(s) to which the notification relates:


                                     PART I
                             REGISTRANT INFORMATION

PS Business Parks, Inc. on behalf of the PS 401(k) Profit Sharing Plan
701 Western Avenue
Glendale, CA, 91201


                                     PART II
                             RULE 12b-25 (b) AND (c)

If the subject report could not be filed without unreasonable effort or expense
and the registrant seeks relief pursuant to Rule 12b-25(b), the following should
be completed. (Check box if appropriate.)

[ ]      (a) The reasons  described  in  reasonable  detail in Part III of
             this form could not be eliminated  without  unreasonable  effort or
             expense;

[X]      (b) The  subject  annual  report,  semi-annual  report,  transition
             report on Form  10-K,  Form  20-F,  Form  11-K,  Form N-SAR or Form
             N-CSR, or portion thereof, will be filed on or before the fifteenth
             calendar day  following  the  prescribed  due date;  or the subject
             quarterly  report or  transition  report on Form  10-Q,  or portion
             thereof,  will  be  filed  on or  before  the  fifth  calendar  day
             following the prescribed due date; and

[ ]      (c) The accountant's  statement or other exhibit required by Rule
             12b-25(c) has been attached if applicable.


                                    PART III
                                    NARRATIVE

State below in reasonable detail why Forms 10-K, 20-F, 11-K, 10-Q, N-SAR, N-CSR,
or the  transition  report or  portion  thereof,  could not be filed  within the
prescribed time period.

The Company is experiencing delays in obtaining information from certain service
providers  to the Plan to provide to the  Company's  external  auditors  for the
completion of the audit report.

Due to the reasons  described  above, the Registrant could not have timely filed
the Form 11-K without  unreasonable effort or expense, and the Form 11-K will be
filed no later than the  fifteenth  calendar day following  the  prescribed  due
date.


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                                     PART IV
                                OTHER INFORMATION

     (1)  Name and  telephone  number  of person  to  contact  in regard to this
          notification:

          Jon Osborne - (818) 244-8080

     (2)  Have all other periodic  reports required under Section 13 or 15(d) of
          the  Securities  Exchange Act of 1934 or Section 30 of the  Investment
          Company Act of 1940 during the preceding 12 months or for such shorter
          period that the  registrant  was required to file such  report(s) been
          filed? If the answer is no, identify report(s).

                                 |X| Yes [ ] No

     (3)  Is it anticipated that any significant change in results of operations
          from  the  corresponding  period  for the  last  fiscal  year  will be
          reflected  by the  earnings  statements  to be included in the subject
          report or portion thereof?

                                 [ ] Yes |X| No

If so: attach an explanation of the  anticipated  change,  both  narratively and
quantitatively, and, if appropriate, state the reasons why a reasonable estimate
of the results cannot be made.

          Not applicable.


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                             PS BUSINESSPARKS, INC.
                                on behalf of the
                          PS 401(k) PROFIT SHARING PLAN


Has  caused  this  notification  to be signed on its  behalf by the  undersigned
thereunto duly authorized.


Date:    June 30, 2005

                        By: /s/ J. Alan Herd 
                            -----------------
                                J. Alan Herd
                                Chairman, Administrative Committee


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