SULLIVAN & WORCESTER LLP
                             One Post Office Square
                           Boston, Massachusetts 02109




                                                    March 28, 1997





Health and Retirement Properties Trust
400 Centre Street
Newton, Massachusetts  02158

Ladies and Gentlemen:

         In connection with the filing of its Annual Report on Form 10-K for the
year ended  December  31, 1996 (the  "Annual  Report") by Health and  Retirement
Properties Trust, a Maryland real estate  investment trust (the "Company"),  the
following  opinion  is  furnished  to you to be filed  with the  Securities  and
Exchange Commission (the "SEC") as Exhibit 8.1 to the Annual Report, to be filed
within one week of 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 the
preparation  of the Annual  Report,  and we have  examined  originals or copies,
certified or otherwise  identified to our  satisfaction,  of the Annual  Report,
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.  Specifically,  and without limiting the generality of the foregoing,
we have reviewed:  the  declaration of trust,  as amended and restated,  and the
by-laws of the Company and the Annual  Report.  We have reviewed the sections in
the Annual  Report  captioned  "Federal  Income Tax  Considerations"  and "ERISA
Plans,  Keogh Plans and  Individual  Retirement  Accounts."  With respect to all
questions of fact on which such opinions are based, we have assumed the accuracy
and  completeness  of and have relied on the information set forth in the Annual
Report and on representations made to us by the officers of the Company. We have
not independently verified such information;  nothing has come to our attention,
however, which would lead us to believe that we are not entitled to rely on such
information.

         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





Health and Retirement Properties Trust
March 28, 1997
Page 2


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,  the "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 federal  income tax and ERISA Laws
matters in the  sections  of the Annual  Report  captioned  "Federal  Income Tax
Considerations"  and  "ERISA  Plans,  Keogh  Plans  and  Individual   Retirement
Accounts," we have made certain assumptions and expressed certain conditions and
qualifications therein, all of which assumptions,  conditions and qualifications
are incorporated herein by reference.

         Based upon and subject to the foregoing, we are of the opinion that the
discussions  with  respect to federal  income tax and ERISA Laws  matters in the
sections of the Annual Report captioned "Federal Income Tax  Considerations" and
"ERISA Plans, Keogh Plans and Individual  Retirement  Accounts," in all material
respects  are accurate and fairly  summarize  the federal  income tax 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.

         We hereby consent to the  incorporation of this opinion by reference as
an exhibit to the Company's  Registration  Statements on Form S-3, No. 333-02863
and 33-62135 and to any references to our firm therein.  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