Sec Form 4 Filing - MATHER ROBIN E @ PS BUSINESS PARKS INC/CA - 2005-03-28

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person MATHER ROBIN E 2. Issuer Name and Ticker or Trading Symbol PS BUSINESS PARKS INC/CA [ PSB] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Vice President (Last) (First) (Middle) 701 WESTERN AVENUE 3. Date of Earliest Transaction (MM/DD/YY) 03/28/2005 (Street) GLENDALE, CA91201-2349 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 03/28/2005 A 2,000 A 6,691 ( 2 ) D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option (right to buy) ( 3 ) $ 44.2 03/15/2005 03/15/2014 Common Stock 2,000 2,000 D Stock Option (right to buy) ( 3 ) $ 44.2 03/15/2006 03/15/2014 Common Stock 2,000 2,000 D Stock Option (right to buy) ( 3 ) $ 44.2 03/15/2007 03/15/2014 Common Stock 2,000 2,000 D Stock Option (right to buy) ( 3 ) $ 44.2 03/15/2008 03/15/2014 Common Stock 2,000 2,000 D Stock Option (right to buy) ( 3 ) $ 44.2 03/15/2009 03/15/2014 Common Stock 2,000 2,000 D Stock Option (right to buy) ( 4 ) $ 31.66 01/10/2004 01/10/2013 Common Stock 1,000 1,000 D Stock Option (right to buy) ( 4 ) $ 31.66 01/10/2005 01/10/2013 Common Stock 1,000 1,000 D Stock Option (right to buy) ( 4 ) $ 31.66 01/10/2006 01/10/2013 Common Stock 1,000 1,000 D Stock Option (right to buy) ( 4 ) $ 31.66 01/10/2007 01/10/2013 Common Stock 1,000 1,000 D Stock Option (right to buy) ( 4 ) $ 31.66 01/10/2008 01/10/2013 Common Stock 1,000 1,000 D Stock Option (right to buy) ( 4 ) $ 28.38 07/03/2002 07/03/2011 Common Stock 833 833 D Stock Option (right to buy) ( 4 ) $ 28.38 07/03/2003 07/03/2011 Common Stock 833 833 D Stock Option (right to buy) ( 4 ) $ 28.38 07/03/2004 07/03/2011 Common Stock 834 834 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other MATHER ROBIN E 701 WESTERN AVENUE GLENDALE, CA91201-2349 Vice President Signatures /s/ David Goldberg, Attorney in Fact 03/30/2005 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Restricted stock units granted on the transaction date which vest 20% on each of the 2nd, 3rd, 4th, 5th, and 6thanniversaries. ( 2 )Includes 6,250 restricted stock units subject to vesting. ( 3 )Stock options granted pursuant to the 2003 Stock Option and Incentive Plan. ( 4 )Stock options granted pursuant to the 1997 Stock Option and Incentive Plan.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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