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                                                                     Exhibit 8.1


June 5, 1998


Brandywine Realty Trust
Brandywine Operating Partnership, L.P.
16 Campus Boulevard
Newtown Square, Pennsylvania  19073



Gentlemen:

We have acted as Tax Advisor to Brandywine Realty Trust (the "Company") and
Brandywine Operating Partnership, L.P. (the "Operating Partnership"), in
connection with the preparation of a registration statement on Form S-3 (the
"Registration Statement"), filed with the Securities and Exchange Commission on
June 5, 1998, with respect to the offering and sale (the "Offering") of (i)
common shares of beneficial interest, preferred shares of beneficial interest,
preferred shares represented by depositary shares (collectively, the "Shares"),
and warrants (the "Warrants") of the Company and (ii) debt securities (the "Debt
Securites") of the Operating Partnership, which may be guaranteed by
unconditional and irrevocable guarantees thereof by the Company (the
"Guarantees"). 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 included therein,
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 Non-Voting 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:

     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



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          discussion contained therein fairly summarizes the federal income tax
          considerations that may be material to holders of the Shares, the
          Warrants and the Debt Securities.

     2.   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.

     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 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, the
Warrants and the Debt Securities. 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. Potential investors in the Shares, the Warrants
and the Debt Securities 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, the Warrants and the Debt Securities, and we hereby consent to such
use of our opinion.


/s/ Arthur Andersen LLP
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ARTHUR ANDERSEN LLP

