EXHIBIT 8.1




                                           February 19, 2002




Senior Housing Properties Trust
400 Centre Street
Newton, Massachusetts  02458

Ladies and Gentlemen:

     In connection with the registration by Senior Housing Properties Trust, a
Maryland real estate investment trust (the "Company"), of its common shares of
beneficial interest, the following opinion is furnished to you to be filed with
the Securities and Exchange Commission (the "SEC") as Exhibit 8.1 to the
Company's Current Report on Form 8-K, filed on the date hereof, under the
Securities Exchange Act of 1934, as amended (the "Exchange Act").

     We have acted as counsel for the Company in connection with its
Registration Statement on Form S-3, File No. 333-76588 (the "Registration
Statement"), under the Securities Act of 1933, as amended (the "Act"). We have
reviewed originals or copies, certified or otherwise identified to our
satisfaction, of corporate records, certificates and statements of officers and
accountants of the Company and of public officials, and such other documents as
we have considered relevant and necessary in order to furnish the opinion
hereinafter set forth. In doing so, we have assumed the genuineness of all
signatures, the legal capacity of natural persons, the authenticity of all
documents submitted to us as originals, the conformity to original documents of
all documents submitted to us as certified or photostatic copies, and the
authenticity of the originals of such documents. Specifically, and without
limiting the generality of the foregoing, we have reviewed: (i) the declaration
of trust, as amended and restated, and the by-laws, as amended and restated, of
the Company; (ii) the prospectus supplement dated February 15, 2002 (the
"Prospectus Supplement") to the final prospectus dated January 30, 2002 (as
supplemented by the Prospectus Supplement, the "Prospectus") which forms a part
of the Registration Statement; and (iii) the Company's Current Report on Form
8-K filed on the date hereof (the "Form 8-K") including the section therein
captioned "Federal Income Tax and ERISA Considerations".





Senior Housing Properties Trust
February 19 2002
Page 2


     The opinion set forth below is based upon the Internal Revenue Code of
1986, as amended, the Treasury Regulations issued thereunder, published
administrative interpretations thereof, and judicial decisions with respect
thereto, all as of the date hereof (collectively, the "Tax Laws"), and upon the
Employee Retirement Income Security Act of 1974, as amended, the Department of
Labor regulations issued thereunder, published administrative interpretations
thereof, and judicial decisions with respect thereto, all as of the date hereof
(collectively, "ERISA Laws"). No assurance can be given that the Tax Laws or the
ERISA Laws will not change. In preparing the discussions with respect to Tax
Laws and ERISA Laws matters in the section of the Form 8-K captioned "Federal
Income Tax and ERISA Considerations", as supplemented by the section of the
Prospectus Supplement captioned "Federal income tax and ERISA considerations",
we have made certain assumptions and expressed certain conditions and
qualifications therein, all of which assumptions, conditions and qualifications
are incorporated herein by reference. With respect to all questions of fact on
which our opinion is based, we have assumed the initial and continuing truth,
accuracy and completeness of: (i) the information set forth in the Form 8-K, the
Prospectus, and in the documents incorporated therein by reference; and (ii)
representations made to us by officers of the Company or contained in the Form
8-K or the Prospectus in each such instance without regard to qualifications
such as "to the best knowledge of" or "in the belief of".

     We have relied upon, but not independently verified, the foregoing
assumptions. If any of the foregoing assumptions are inaccurate or incomplete
for any reason, if the transactions described in the Form 8-K or the Prospectus,
or the documents incorporated therein by reference, have been consummated in a
manner that is inconsistent with the manner contemplated therein, or if the
issuance of the common shares of beneficial interest is consummated in a manner
that is inconsistent with the manner in which it is described in the Prospectus,
our opinion as expressed below may be adversely affected and may not be relied
upon.

     Based upon and subject to the foregoing, we are of the opinion that the
discussions with respect to Tax Laws and ERISA Laws matters in the section of
the Form 8-K captioned "Federal Income Tax and ERISA Considerations", as
supplemented by the section in the Prospectus Supplement captioned "Federal
income tax and ERISA considerations", in all material respects are accurate and
fairly summarize the Tax Laws issues and ERISA Laws issues addressed therein,
and hereby confirm that the opinions of counsel referred to in said sections
represent our opinions on the subject matter thereof.

     Our opinion above is limited to the matters specifically covered hereby,
and we have not been asked to address, nor have we addressed, any other matters
or any other transactions. Further, we disclaim any undertaking to advise you of
any subsequent changes of the matters stated, represented or assumed herein or
any subsequent changes in the Tax Laws or ERISA Laws.





Senior Housing Properties Trust
February 19 2002
Page 3


     We hereby consent to the incorporation of this opinion by reference as an
exhibit to the Registration Statement and to the reference to our firm in the
Prospectus. In giving such consent, we do not thereby admit that we come within
the category of persons whose consent is required under Section 7 of the Act or
under the rules and regulations of the SEC promulgated thereunder.

                                              Very truly yours,

                                              /s/ Sullivan & Worcester LLP
                                              SULLIVAN & WORCESTER LLP