FIFTEENTH AMENDMENT TO AMENDED AND RESTATED AGREEMENT OF LIMITED PARTNERSHIP OF BRANDYWINE OPERATING PARTNERSHIP, L.P.

FIFTEENTH AMENDMENT TO AMENDED AND RESTATED

AGREEMENT OF LIMITED PARTNERSHIP

OF

BRANDYWINE OPERATING PARTNERSHIP, L.P.

THIS FIFTEENTH AMENDMENT, dated as of August 15, 2006 (the “Amendment”), further amends the Amended and Restated Agreement of Limited Partnership Agreement (as amended to date, the “Partnership Agreement”) of BRANDYWINE OPERATING PARTNERSHIP, L.P., a Delaware limited partnership (the “Partnership”). Capitalized terms used herein but not defined herein shall have the meanings given such terms in the Partnership Agreement.

BACKGROUND

A. Pursuant to the Partnership Agreement, Brandywine Realty Trust (the “General Partner”), as the general partner of the Partnership, has the power and authority to issue additional Partnership Interests to persons on such terms and conditions as the General Partner may deem appropriate.

B. The General Partner, pursuant to the exercise of such power and authority and in accordance with the Partnership Agreement, has determined to execute this Amendment to the Partnership Agreement to evidence the issuance of additional Partnership Interests consisting of Class A Units and the admission of the holders of such Partnership Interests as Limited Partners of the Partnership pursuant to the Agreement of Sale dated as of July 25, 2006 (the “Agreement of Sale”) among the General Partner, the Partnership, MJV, LLC, MJV 2355, LLC, Dulles 243 LLC (“Dulles”), Norman Perlmutter (“Perlmutter”) and Eric D. Mayer (“Mayer”).

C. Pursuant to the Agreement of Sale, the Partnership issued on the date hereof an aggregate of 424,608 Class A Units to Dulles (evidenced by Certificate A - 169). Pursuant to an assignment, executed on the date hereof, Dulles assigned and transferred its entire right, title and interest in and to 134,898 of such Class A Units to Bell Atlantic Master Trust (“BAMT”); and pursuant to an assignment, executed on the date hereof (the “Assignment to PIC”), Dulles assigned and transferred its entire right, title and interest in and to 289,710 of such Class A Units to PIC 243 LLC (“PIC”). Following such assignments and transfers by Dulles, Certificate A - 169 was cancelled and Certificate A - 170 (evidencing 134,898 Class A Units) was issued to BAMT and Certificate A - 171 (evidencing 289,710 Class A Units) was issued to PIC. Pursuant to an assignment, executed on the date hereof immediately after the execution of the Assignment to PIC and the assignment and transfer effected thereby, PIC assigned and transferred its entire right, title and interest in and to 50% of the Class A Units received by it from Dulles to Perlmutter and assigned and transferred its entire right, title and interest in and to the remaining 50% of the Class A Units received by it from Dulles to Mayer. Following such assignments and transfers by PIC, Certificate A - 171 was cancelled and Certificate A - 172 (evidencing 144,855 Class A Units) was issued to Perlmutter and Certificate A - 173 (evidencing 144,855 Class A Units) was issued to Mayer. Accordingly, as of the date hereof and after giving effect to the foregoing assignments, neither Dulles nor PIC owns any Class A Units, and BAMT owns 134,898 Class A Units and each of Perlmutter and Mayer owns 144,855 Class A Units. BAMT, Perlmutter and Mayer are referred to below as the “Admitted Continuing Partners” and Dulles and PIC are referred to below as the “Withdrawn Partners.”