Please visit our website at www.psbusinessparks.com where you will find a direct link to information on this portfolio entitled “Northern California Industrial Flex Portfolio Acquisition” on the home page.The Company will host a conference call on Wednesday, December 21, 2011, at 9:00 a.m. (PST) to discuss the acquisition in more detail. The toll free number is (888) 299-3246; the conference ID is 38450701. The call will also be available via a live webcast on the Company’s website. A replay of the conference call will be available through December 28, 2011 at (855) 859-2056. A replay of the conference call will also be available on the Company’s website. Company Information PS Business Parks, Inc., a member of the S&P SmallCap 600, is a self-advised and self-managed equity real estate investment trust (“REIT”) that acquires, develops, owns and operates commercial properties, primarily multi-tenant flex, office and industrial space. The Company defines “flex” space as buildings that are configured with a combination of office and warehouse space and can be designed to fit a number of uses (including office, assembly, showroom, laboratory, light manufacturing and warehouse space). As of December 20, 2011, the Company wholly owned 27.2 million rentable square feet with approximately 4,360 customers located in eight states, concentrated in California (11.1 million sq. ft.), Virginia (4.2 million sq. ft.), Florida (3.7 million sq. ft.), Texas (3.3 million sq. ft.), Maryland (2.4 million sq. ft.), Oregon (1.3 million sq. ft.), Arizona (0.7 million sq. ft.) and Washington (0.5 million sq. ft.). Additional information about PS Business Parks, Inc. is available on the Company’s website at www.psbusinessparks.com. Forward-Looking Statements When used within this press release, the words “may,” “believes,” “anticipates,” “plans,” “expects,” “seeks,” “estimates,” “intends” and similar expressions are intended to identify “forward-looking statements.” Such forward-looking statements involve known and unknown risks, uncertainties and other factors, which may cause the actual results and performance of the Company to be materially different from those expressed or implied in the forward-looking statements. Such risks, uncertainties and other factors relate to, among others, difficulties encountered in integrating the properties, inability to realize expected synergies, unanticipated operating costs, unexpected declines in occupancy, and the effects of general and local economic and real estate conditions. Additional factors which could impact the forward-looking statements contained in this press release are contained in the company’s filings with the Securities and Exchange Commission. PS Business Parks, Inc. assumes no obligation to update or supplement forward-looking statements that become untrue because of subsequent events.