EXHIBIT A
VOTING AGREEMENT

VOTING AGREEMENT

     VOTING AGREEMENT, dated as of October 3, 2005 (this “Agreement”), among
Brandywine Realty Trust, a Maryland real estate investment trust (“Parent”),
Brandywine Operating Partnership, L.P., a Delaware limited partnership (“Parent
L.P.”and, together with Parent, the “Parent Entities”),and the undersigned
holder (the “Holder”)of common shares of beneficial interest, par value $.01 per
share (“Company Common Shares”),of Prentiss Properties Trust, a Maryland real
estate investment trust (the “Company”).

     WHEREAS, as of the date hereof, Holder beneficially owns the number of
Company Common Shares and the number of Company Common Units set forth on the
Holder signature page hereto (all other Company Common Shares so owned and all
Company Common Shares that may hereafter be acquired by Holder prior to the
Expiration Date (as defined in Section 3.4 hereof), whether upon exercise of
options, purchase, dividend, distribution or otherwise, being referred to herein
as such Holder’s “Company Shares” and all other Company Common Units so owned
and all other Company Common Units that may hereafter be acquired by Holder
prior to the Expiration Date, whether upon exercise of options, purchase,
dividend, distribution or otherwise, being referred to herein as such Holder’s
“Company Units”);

     WHEREAS, Parent, Parent L.P., Brandywine Cognac I, LLC, a Maryland limited
liability company and subsidiary of Parent L.P. (“Merger Sub”), Brandywine
Cognac II, LLC, a Delaware limited liability company and subsidiary of Parent
L.P. (“L.P. Merger Sub”), the Company and Prentiss Properties Acquisition
Partners, L.P., a Delaware limited partnership (“Company L.P.”) have entered
into an Agreement and Plan of Merger, dated as of October 3, 2005 (the “Merger
Agreement”), which provides, upon the terms and subject to the conditions set
forth therein, for the merger of Merger Sub with the Company (the “REIT
Merger”); and

     WHEREAS, as a condition to the willingness of Parent, Parent L.P., Merger
Sub and L.P. Merger Sub to enter into the Merger Agreement, the Parent Entities
have required that Holder agree, and in order to induce the Parent Entities to
enter into the Merger Agreement, Holder has agreed, to enter into this
Agreement.

     Capitalized terms used but not otherwise defined in this Agreement have the
meanings assigned to such terms in the Merger Agreement.

     NOW, THEREFORE, in consideration of the representations, warranties,
covenants and agreements contained in this Agreement, and other good and
valuable consideration, the receipt and adequacy of which are hereby
acknowledged, and intending to be legally bound hereby, the parties hereto agree
as follows:

Article I.

VOTING OF COMPANY COMMON SHARES AND COMPANY COMMON UNITS

     Section 1.1.     Voting Agreements.     Until the Expiration Date, at every
meeting of the shareholders of the Company called, and at every adjournment
thereof, and on every action or approval by written consent of the shareholders
of the Company, Holder (in its capacity as such) shall vote or cause its Company
Shares to be voted (i) in favor of approval of the Merger Agreement and the REIT
Merger, (ii) in favor of each of the other transactions contemplated by the
Merger Agreement and (iii) in favor of any incidental matter reasonably
determined by the Parent Entities to be necessary in order to facilitate
consummation of the REIT Merger. At any meeting of the shareholders of the
Company, or at any adjournment thereof, or in any other circumstances upon which
their vote, consent or other approval is sought, such Holder shall vote (or
cause to be voted) the Company Shares against (i) any Takeover Proposal or any
action which is a component of any Takeover Proposal, (ii) any merger agreement
or merger (other than the Merger Agreement, the REIT Merger and the OP Merger),
reorganization, recapitalization, dissolution, liquidation or winding up of or
by the Company, (iii) any amendment of the Company Organizational Documents,
which amendment would result in a breach of a representation, warranty or
covenant of the Company under the Merger Agreement or would in any manner
prevent or materially impede, interfere with or delay the REIT Merger, the OP
Merger, the Merger Agreement or any of the other transactions contemplated by
the Merger Agreement or (iv) any other matter that is inconsistent with the
prompt consummation of the REIT Merger, the OP Merger and the other transactions
contemplated by the Merger Agreement (each of clauses (i), (ii), (iii) and (iv),
a “Competing REIT Transaction”).

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     Section 1.2.      Grant of Irrevocable Proxy with Respect to Company
Shares.     (a) Holder hereby irrevocably (to the fullest extent permitted by
law) appoints Gerard H. Sweeney and Walter D’Alessio, and each of them, as
Holder’s sole and exclusive attorneys and proxies, with full power of
substitution and re-substitution, to vote the Company Shares and to exercise all
voting, consent and similar rights of Holder with respect to the Company Shares
(including, without limitation, the power to execute and deliver written
consents) at every annual, special or adjourned meeting of shareholders of the
Company and in every written consent in lieu of such meeting (i) in favor of
approval of the Merger Agreement and the REIT Merger, (ii) in favor of each of
the other transactions contemplated by the Merger Agreement, (iii) in favor of
any incidental matter reasonably determined by the Parent Entities to be
necessary in order to facilitate the REIT Merger and (iv) against any Competing
REIT Transaction. It is understood and agreed that the attorneys and proxies
named above may not exercise these voting rights on any other matter except as
provided above. Except as set forth in this Agreement, Holder may vote the
Company Shares on all other matters.

          (b)      Upon Holder’s execution of this Agreement, any and all prior
proxies given by Holder with respect to any Company Shares with respect to the
matters contemplated by Section 1.2(a) are hereby revoked.

          (c)      Holder hereby affirms that the proxy set forth in this
Section 1.2 is irrevocable (to the fullest extent permitted by law), is coupled
with an interest and is granted in consideration of the Parent Entities entering
into the Merger Agreement. Holder hereby ratifies and confirms all that such
irrevocable proxy may lawfully do or cause to be done by virtue hereof. Such
irrevocable proxy is executed and intended to be irrevocable in accordance with
the provisions of the MGCL.

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     Section 1.3.      Transfer of Company Shares and Company Units.

          (a)      Transferee of Company Shares and Company Units to be Bound by
this Agreement. Holder agrees that, during the period from the date of this
Agreement through the Expiration Date, other than by operation of Law as part of
the REIT Merger or the OP Merger or in any offer to exchange Company Units as
contemplated under Section 1.11 of the Merger Agreement, or the redemption or
conversion of Company Common Units, Holder shall not cause or permit any
Transfer (as defined below) of any of the Company Shares or Company Units to be
effected without Parent’s prior written consent to such Transfer and unless each
Person to which any of such Company Shares or Company Units, or any interest in
any of such Company Shares or Company Units, is or may be Transferred shall
have: (a) executed a counterpart of this Agreement and (b) agreed in writing to
hold such Company Shares or Company Units (or interest in such Company Shares or
Company Units) subject to all of the terms and provisions of this Agreement;
provided, however, that Holder shall be entitled to Transfer Company Units (or
any interest in such Company Units) to an immediate family member (or trust for
the benefit of an immediate family member) or an Affiliate of such Holder if
such family member, trust or Affiliate shall have (1) executed a counterpart of
this Agreement and (2) agreed in writing to hold such Company Units (or interest
in such Company Units) subject to all of the terms and provisions of this
Agreement. A Person shall be deemed to have effected a “Transfer”of a security
if such person directly or indirectly: (i) sells, pledges, encumbers, grants an
option with respect to, transfers or disposes of such security or any interest
in such security; or (ii) enters into an agreement or commitment providing for
the sale of, pledge of, encumbrance of, grant of an option with respect to,
transfer of or disposition of such security or any interest therein.

          (b)      Transfer of Voting Rights. Holder agrees that, during the
period from the date of this Agreement through the Expiration Date, Holder shall
not deposit (or permit the deposit of) any Company Shares or Company Units in a
voting trust or grant any proxy or enter into any voting agreement or similar
agreement in contravention of the obligations of Holder under this Agreement
with respect to any of the Company Shares and Company Units.

     Section 1.4.      No Inconsistent Actions by Holder. While this Agreement
is in effect, Holder shall not revoke or rescind, or purport to revoke or
rescind, the proxies granted hereby or take any action inconsistent with the
provisions of this Agreement.

     Section 1.5.      Additional Documents. Holder (in its capacity as such)
hereby covenants and agrees to execute and deliver any additional documents
necessary or desirable, in the reasonable opinion of Parent, to carry out the
intent of this Agreement.

     Section 1.6.      No Solicitation. (a) Holder shall not, and shall use its
reasonable best efforts to cause its Affiliates or Representatives not to,
directly or indirectly (i) solicit, initiate, encourage or knowingly take any
other action to facilitate (including by the furnishing of non-public
information) the submission of any inquiry, proposal or offer from any Person
(other than Parent, Merger Sub or their Affiliates) relating to, or that could
reasonably be expected to lead to, any Takeover Proposal, (ii) agree to, approve
or recommend any Takeover Proposal or enter into any agreement with respect to
any Takeover Proposal or (iii) enter into, continue or otherwise participate in
any discussions or negotiations regarding, or furnish to any Person any
non-public information with respect to, or take any other action to facilitate
any inquiries or the making of any proposal that constitutes, or could
reasonably be expected to lead to, any Takeover Proposal; provided, however,
that the foregoing does not restrict any Holder that is a member of the Company
Board or an officer of the Company from taking any actions in such capacity to
the extent permitted by the Merger Agreement.

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          (b) In addition to the obligations of Holder set forth in paragraph
(a) of this Section 1.6, Holder shall notify Parent promptly (but in any event
within two business days) after receipt or occurrence of (i) any Takeover
Proposal, (ii) any request for information with respect to any Takeover
Proposal, (iii) any inquiry, proposal, discussions or negotiation with respect
to any Takeover Proposal and (iv) the material terms and conditions of any such
Takeover Proposal, request for information, inquiry, proposal, discussion or
negotiation and the identity of the Person making any such Takeover Proposal,
request for information, inquiry or proposal or with whom discussions or
negotiations are taking place. In the event Holder shall receive or become aware
of any Takeover Proposal subsequent to the date hereof, Holder shall keep Parent
informed in all material respects of the status and details (including
amendments or proposed amendments) of any such inquiry, request or Takeover
Proposal.

Article II.

REPRESENTATIONS AND WARRANTIES

     Section 2.1.       Representations And Warranties Of Holder.     Holder
hereby represents and warrants to the Parent Entities as follows:

          (a)      Due Organization, Authorization, etc. Holder has all
requisite legal capacity, power and authority to execute and deliver this
Agreement and to consummate the transactions contemplated hereby. The execution
and delivery of this Agreement and the consummation of the transactions
contemplated hereby have been duly authorized by all necessary action on the
part of Holder. This Agreement has been duly executed and delivered by or on
behalf of Holder and, assuming its due authorization, execution and delivery by
the Parent Entities, constitutes a legal, valid and binding obligation of
Holder, enforceable against Holder in accordance with its terms.

          (b)      No Conflicts, Required Filings and Consents.

                    (i)      The execution and delivery of this Agreement by
Holder does not, and the performance of this Agreement by Holder will not,
(i) conflict with or violate any judgment, order, decree, statute, Law,
ordinance, rule or regulation applicable to Holder or by which Holder or any of
Holder’s assets or properties is bound or affected or (ii) violate or conflict
with any Contract to which Holder is a party or by which any of its assets or
properties is bound.

                    (ii)      The execution and delivery of this Agreement by
Holder does not, and the performance of this Agreement by Holder will not,
require any consent, approval, order or authorization of, or registration,
declaration or filing with, or permit from, any Governmental Entity.

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                    (iii)      Except for this Agreement, there are no voting
trusts or other agreements or understandings, including, without limitation, any
proxies, in effect governing the voting of the Company Shares or the Company
Units.

          (c)      Title to Company Shares and Company Units. Holder is the
beneficial owner of the Company Common Shares and the Company Common Units set
forth on the Holder’s signature page hereto and holds sole and full voting
rights with respect thereto other than as set forth in Sections 1.1 and 1.2
hereof. On the date hereof, Holder does not beneficially own any other Company
Common Shares or Company Common Units (or any other securities or interests in
the Company or Company L.P. other than pursuant to existing stock options
granted under Company Incentive Plans). No other Person has any voting rights
with respect to the Company Common Shares or the Company Units. In addition, the
Company Common Shares and the Company Common Units held by Holder are free and
clear of any Encumbrances that would adversely affect the ability of Holder to
carry out the terms of this Agreement.

          (d)      Reliance on Information. Holder understands and acknowledges
that the Parent Entities are entering into the Merger Agreement in reliance upon
the execution and delivery of this Agreement by Holder.

     Section 2.2.       Representations And Warranties Of Parent and Parent L.P.
     Parent and Parent L.P. hereby jointly and severally represent and warrant
to Holder that: (i) each of Parent and Parent L.P. has all requisite power and
authority to execute and deliver this Agreement and to consummate the
transactions contemplated hereby; (ii) the execution and delivery of this
Agreement and the consummation of the transactions contemplated hereby have been
duly authorized by all necessary action on the part of each of Parent and Parent
L.P.; and (iii) this Agreement has been duly executed and delivered by or on
behalf of each of Parent and Parent L.P. and, assuming its due authorization,
execution and delivery by Holder, constitutes a legal, valid and binding
obligation of each of each of Parent and Parent L.P., enforceable against each
of Parent and Parent L.P. in accordance with its terms.

Article III.

MISCELLANEOUS

     Section 3.1.       Expenses.     Except as otherwise provided herein, all
costs and expenses incurred in connection with the transactions contemplated by
this Agreement shall be paid by the party incurring such costs and expenses.

     Section 3.2.      Notices.     All notices and other communications
hereunder shall be in writing and shall be deemed duly given (a) on the date of
delivery if delivered personally, or by facsimile, upon confirmation of receipt,
(b) on the first business day following the date of dispatch if delivered by a
recognized next-day courier service, or (c) on the fifth business day following
the date of mailing if delivered by registered or certified mail, return receipt
requested, postage prepaid. All notices hereunder shall be delivered as set
forth below, or pursuant to such other instructions as may be designated in
writing by the party to receive such notice:

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(i)      if to the Parent Entities to:

          Brandywine Realty Trust
          401 Plymouth Road
          Plymouth Meeting, PA 19462
          Attn: General Counsel
          Facsimile: (610) 832-4928

          with a copy to:

          Pepper Hamilton LLP
          3000 Two Logan Square
          Philadelphia, PA 19103
          Attention: Michael H. Friedman, Esq.
          Facsimile: (215) 981-4750

(ii)      if to Holder to:

          Prentiss Properties Trust
          3890 West Northwest Highway
          Suite 400,
          Dallas, Texas 75220          
          Attention: General Counsel
          Facsimile: (214)358-6443

          with a copy to:

          Akin Gump Strauss Hauer & Feld LLP
          1700 Pacific Avenue, Suite 4100
          Dallas, Texas 75201
          Attention: Michael E. Dillard, P.C.
          Fax No.: (214) 969-4343

     Section 3.3.       Incorporation of Other Provisions.     Sections 9.04,
9.05, 9.06, 9.08 and 9.10 of the Merger Agreement are hereby incorporated by
reference and made a part of this Agreement, mutatis mutandis, as if restated in
full herein and without regard to whether the Merger Agreement remains in
effect.

     Section 3.4.      Termination.     Unless terminated earlier upon the
written agreement of each of the parties hereto, this Agreement and the proxies
provided herein shall terminate (the “Expiration Date”) and be of no further
force and effect, automatically and without any required action of the parties
hereto, upon the earlier to occur of (i) the Effective Time or (ii) such date
and time as the Merger Agreement shall have been validly terminated pursuant to
Section 8.01 thereof; provided that no such termination shall relieve any party
of liability for a breach hereof prior to termination. Notwithstanding the
foregoing, Section 3.1 hereof shall survive the Expiration Date in accordance
with its terms.

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     Section 3.5.      Amendment.     This Agreement may not be amended,
modified or rescinded except by an instrument in writing signed by each of the
parties hereto.

     Section 3.6.      Capacity.      No Holder entering into this Agreement who
is or becomes during the term hereof a trustee or officer of the Company makes
any agreement or understanding herein in his capacity as a trustee or officer.
Holders signs solely in his capacity as the beneficial owner of his Company
Shares and Company Units.

     Section 3.7.      Entire Agreement.     This Agreement, together with the
documents expressly referred to herein, constitutes the entire agreement, and
supersede all prior agreements and understandings, both written and oral, among
the parties with respect to the subject matter hereof.

     Section 3.8.      Assignment.       Neither this Agreement nor any of the
rights, interests or obligations under this Agreement shall be assigned, in
whole or in part, by operation of law or otherwise by any of the parties without
the prior written consent of the other parties. Any purported assignment without
such consent shall be void. Subject to the preceding sentences, this Agreement
will be binding upon, inure to the benefit of, and be enforceable by, the
parties and their respective successors and assigns.

[Signature Pages Follow]

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     IN WITNESS WHEREOF, Parent and Parent L.P. have caused this Agreement to be
executed by their respective officers thereunto duly authorized and Holder has
caused this Agreement to be duly executed by an authorized signatory, all as of
the date first written above.

  Brandywine Realty Trust       By: /s/ Gerard H. Sweeney             Name:
Gerard H. Sweeney   Title: President and Chief Executive Officer      
Brandywine Operating Partnership, L.P.                      Brandywine Realty
Trust,              its general partner                  By: /s/ Gerard H.
Sweeney                        Name: Gerard H. Sweeney              Title:
President and Chief Executive Officer

          HOLDER       By: /s/ Michael V. Prentiss             Name: Michael V.
Prentiss     Dated: __________, 2005 Print Name of Holder:       Address of
Holder:   fax: __________       Company Shares beneficially owned:  
           Company Common Shares_________________              Company Common
Shares   issuable upon exercise of outstanding options_____   Company Units
beneficially owned:              Company Common Units_______________

 

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