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                                                                     Exhibit 8.1


                                  May 22, 1998



Brandywine Realty Trust
16 Campus Boulevard
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-3 (the
"Registration Statement"), filed with the Securities and Exchange Commission on
May 22, 1998, 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. Capitalized terms not otherwise defined herein shall have the meaning
set forth in the Registration Statement.

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 schedules 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 LLP that the shares of NonVoting
Preferred Stock issued by Brandywine Realty Services Corporation to Brandywine
Operating Partnership, L.P. do not constitute voting securities for purposes of
the Investment Company Act of 1940. 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, 1997. In addition, we prepared the Company's federal and state tax
returns from 1986 through 1988, and 1996.

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

         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 the holders of the Shares.

         The Operating Partnership and the Title Holding Partnerships have at
         all times 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.




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         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 current method of organization and 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 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. 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. Potential
investors in the Shares are urged to seek and rely on the tax advice of a
qualified professional. 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.


/s/ARTHUR ANDERSEN LLP



