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                                                                    EXHIBIT 8.1
November 21, 1996


Brandywine Realty Trust
16 Campus Boulevard
Suite 150
Newtown Square, Pennsylvania  19073


Gentlemen:

We have acted as Tax Advisor to Brandywine Realty Trust (the "Company"), in
connection with the preparation of a registration statement on Form S-11 (the
"Registration Statement"), initially filed with the Securities and Exchange
Commission on October 11, 1996 (No. 333-13969), with respect to the offering and
sale (the "Offering") of common shares of beneficial interest (the "Shares") of
the Company. You have requested our opinion on certain federal income tax
matters in connection with the Offering.

In rendering the opinions expressed herein, we have examined such documents and
other matters as we have deemed necessary or appropriate, including (but not
limited to) the Registration Statement and the Prospectus, representation
letters provided by the Company to us and legal counsel, and schedules
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prepared by the Company which relate to the Company's compliance with various
REIT qualification tests. Further, we have obtained additional information and
representations from officers of the Company with respect to various factual
matters relating to the Company's operations and stock ownership and to the
Company's expectations to continue to meet certain diversity of ownership tests
on a basis consistent with past practice and of its intention to operate in a
manner consistent with its past operations, subject to any changes described in
the Prospectus. We have relied on the opinion of Pepper, Hamilton & Scheetz that
Brandywine Holdings I, Inc. is duly organized and incorporated under
Pennsylvania law. We have also relied on good standing certificates obtained
from the Secretary of State that certain partnerships are in good standing under
the laws of their respective jurisdiction of formation. In addition, we have
relied upon the authenticity of the documents, and upon the accuracy of the
representations, described above.

Our past material professional relationship with the Company has consisted of
rendering opinions on the Company's financial statements under generally
accepted accounting principles from 1986 through the calendar year-ending
December 31, 1995. In addition, we prepared the Company's federal and state tax
returns from 1986 through 1988.

Based upon and subject to the foregoing, it is our opinion that:

      1. The descriptions of the federal income tax conclusions contained in the
         Prospectus under the caption "Federal Income Tax Considerations" are
         correct in all material respects, and the discussion contained therein
         fairly summarizes the federal income tax considerations that may be
         material to a holder of the common shares.

      2. The Operating Partnership and the Title Holding Partnerships have at
         all time been and will continue to be treated for federal income tax
         purposes as partnerships and not as associations taxable as
         corporations or as publicly traded partnerships.

      3. Beginning with its taxable year ended December 31, 1986, the Company
         was organized and has operated in conformity with the requirements for
         qualification as a REIT under the Code for each of its taxable years
         and the Company's proposed method of operation will enable it to
         continue to so qualify.

The opinion expressed herein is based upon the Code, the Treasury Department's
regulations which interpret the Code, and relevant judicial and administrative
precedent, all of which are subject to change, on a retroactive basis, at any
time. Any such changes could adversely impact the opinion rendered herein and
the tax consequences to the Company and the investors in the Shares. During the
course of our engagement, after reasonable investigation, nothing has come to
our attention which would cause us to question the accuracy of the documents or
other information provided to us by the Company or the veracity of the
information or representations provided to us by the Company or Company's
counsel. As noted above, the examination of these documents, the accumulation of
the information contained therein and representations of the Company and its
counsel formed a material part of the basis on which we
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November 21, 1996


formed our opinion. Should anything occur, or already have occurred, that would
compromise the accuracy of the aforementioned documents or the veracity of the
aforementioned information and representations, our opinion as expressed herein
may not be relied upon.

Our opinion is valid as of the date of this letter. We have not been retained,
nor are we obligated, to monitor or update this opinion for future conditions
that may affect this opinion. Potential investors in the Shares are urged to
seek and rely on the tax advice of a qualified professional. Our opinion is
limited to the tax matters specifically enumerated within and we have not
considered any other federal income tax matters, any state or local income tax
issues, nor any non U.S. tax issues, potentially impacting upon an investment in
the Shares. The opinion expressed herein is not binding upon the IRS and should
not be construed to indicate IRS approval of the Company's qualifying status as
a REIT for the years considered herein. The opinions expressed herein reflect
our assessment of the outcome of litigation and other adversarial proceedings
based on an analysis of the existing tax authorities relating to the issues. It
is important to note, however, no assurance can be given that the Company would
in fact litigate any of the matters addressed herein.

We understand that our opinion will be attached as an Exhibit to the
Registration Statement and will be referred to in the Prospectus that is part of
the Registration Statement which will be delivered to prospective purchasers of
the Shares, and we hereby consent to such use of our opinion.

ARTHUR ANDERSEN LLP
