Exhibit 8.1

                      [Letterhead of Sullivan & Worcester]





                                                                   June 21, 2001




Senior Housing Properties Trust
SNH Capital Trust I
c/o 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"), and SNH Capital Trust I
(the "Trust"), of $25,000,000 of 10.125% Trust Preferred Securities due June 15,
2041 (the "Trust Preferred  Securities"),  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, to be filed within one
week of the date hereof,  under the Securities  Exchange Act of 1934, as amended
(the "Exchange Act").

         The Trust Preferred Securities represent undivided beneficial interests
in the assets of the Trust. The Trust's assets will consist of up to $29,639,200
(including exercise of the over-allotment  option) aggregate principal amount of
10.125%  junior   subordinated   debentures  due  June  15,  2041  (the  "Junior
Subordinated  Debentures") to be issued by the Company. We have acted as counsel
for the Company and the Trust in connection with the  Registration  Statement on
Form  S-3,  File  No.  333-60392  (the  "Registration  Statement"),   under  the
Securities Act of 1933, as amended (the "Act").  Capitalized  terms used in this
opinion  letter and not  otherwise  defined  herein have the same meaning as set
forth in the Registration Statement.

         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 the Trust 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


Senior Housing Properties Trust
SNH Capital Trust I
June 21, 2001
Page 2


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
declaration  of  trust,  as  amended  and  restated,  of the  Trust;  (iii)  the
prospectus  supplement dated June 18, 2001 (the "Prospectus  Supplement") to the
final  prospectus  dated  May  21,  2001  (as  supplemented  by  the  Prospectus
Supplement,  the "Prospectus") which forms a part of the Registration Statement;
(iv) the Certificate of Trust of the Trust;  (v) the form of the Trust Preferred
Securities and Trust common securities and specimen  certificates  thereof; (vi)
the Guarantee Agreement,  the Agreement as to Expenses and Liabilities,  and the
Junior  Subordinated  Indenture,  as  supplemented;  and (vii) the  Underwriting
Agreement  and such other  documents  and  corporate  records as we have  deemed
necessary or appropriate  for purposes of our opinion (the  foregoing  items (i)
through (vii), collectively,  the "Offering Documents");  and (viii) the section
in the  Company's  Form 10-K for the year ended  December  31, 2000 (the "Annual
Report") captioned "Federal Income Tax Considerations."

         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"). No assurance
can be given that the Tax Laws will not change.  In  preparing  the  discussions
with respect to Tax Laws matters in the section of the Annual  Report  captioned
"Federal  Income  Tax  Considerations"  and in  the  section  of the  Prospectus
Supplement  captioned "Federal Income Tax  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 Annual Report, the Offering Documents,  and
in the documents incorporated therein by reference; (ii) representations made to
us by  officers  of the Company or  contained  in the Annual  Report or Offering
Documents,  in each such instance without regard to  qualifications  such as "to
the best knowledge of" or "in the belief of"; and (iii) the assumption  that the
Offering  Documents have been and will continue to be fully complied with by all
parties  thereto without  amendment or waiver,  and that there are not any other
arrangements,  understandings,  or agreements  among any of the parties  thereto
other than those expressly set forth in the Offering Documents.

         We have relied upon,  but not  independently  verified,  the  foregoing
assumptions.  If any of the foregoing  assumptions  are inaccurate or incomplete
for any reason, or if the issuance of the Trust Preferred  Securities and Junior
Subordinated Debentures is consummated in a manner that is inconsistent with the
manner in which it is  described  in the  Offering  Documents,  our  opinion  as
expressed below may be adversely affected and may not be relied upon.


Senior Housing Properties Trust
SNH Capital Trust I
June 21, 2001
Page 3


         Based solely upon and subject to the  foregoing,  we are of the opinion
that under current United States federal income tax law:

         1.       The Trust will be  classified as a grantor trust and not as an
                  association subject to tax as a corporation. Accordingly, each
                  holder  of  Trust  Preferred   Securities  will  generally  be
                  considered  the owner of an  undivided  interest in the Junior
                  Subordinated Debentures.

         2.       The  Junior  Subordinated  Debentures  will be  classified  as
                  indebtedness of the Company.

         3.       The discussion with respect to Tax Laws matters in the section
                  of  the   Annual   Report   captioned   "Federal   Income  Tax
                  Considerations,"  as  supplemented  by the  discussion  in the
                  Prospectus    Supplement   captioned   "Federal   Income   Tax
                  Considerations,"  in all  material  respects is  accurate  and
                  fairly summarizes the Tax Laws issues addressed therein.

         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.

         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,  and to the  incorporation  of  this  opinion  by  reference  in the
Company's  Registration  Statement.  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