SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                 SCHEDULE 13D/A
                                 (Rule 13d-101)

             INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
             TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT
                                TO RULE 13d-2(a)
                               (Amendment No. 4)*

                         SENIOR HOUSING PROPERTIES TRUST
                                (Name of Issuer)

              COMMON SHARES OF BENEFICIAL INTEREST, $.01 PAR VALUE
                         (Title of Class of Securities)

                                   81721M 10 9
                                 (CUSIP Number)

                                 John A. Mannix
                              HRPT Properties Trust
                                400 Centre Street
                                Newton, MA 02458
                                 (617) 332-3990
           (Name, Address and Telephone Number of Person Authorized to
                      Receive Notices and Communications)

                                February 21, 2002
             (Date of Event which Requires Filing of this Statement)


If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box
/ /.

Note: Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 13d-7(b) for other
parties to whom copies are to be sent.

                         (Continued on following pages)

                               (Page 1 of 8 Pages)

-------------------------

* The remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for  any  subsequent   amendment   containing   information  which  would  alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).




--------------------------------------------------------------------------------
1           NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)


            HRPT Properties Trust  I.R.S. ID No. 04-6558834
--------------------------------------------------------------------------------
2           CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*            (a) [ ]
                                                                         (b) [ ]

--------------------------------------------------------------------------------
3           SEC USE ONLY


--------------------------------------------------------------------------------
4           SOURCE OF FUNDS*


            WC
--------------------------------------------------------------------------------
5           CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) OR 2(e)                                               [ ]


--------------------------------------------------------------------------------
6           CITIZENSHIP OR PLACE OF ORGANIZATION


            Maryland
--------------------------------------------------------------------------------
                          7         SOLE VOTING POWER
       NUMBER OF
         SHARES
      BENEFICIALLY                  12,809,238
        OWNED BY          ------------------------------------------------------
          EACH            8         SHARED VOTING POWER
       REPORTING
         PERSON
          WITH
                          ------------------------------------------------------
                          9         SOLE DISPOSITIVE POWER


                                    12,809,238
                          ------------------------------------------------------
                          10        SHARED DISPOSITIVE POWER


--------------------------------------------------------------------------------
11          AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON


            12,937,493
--------------------------------------------------------------------------------
12          CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES*                                                          [ ]


--------------------------------------------------------------------------------
13          PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)


            22.14%
--------------------------------------------------------------------------------
14          TYPE OF REPORTING PERSON*


            00
--------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!

--------------------------------------------------------------------------------
1           NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)


            REIT Management & Research LLC
--------------------------------------------------------------------------------
2           CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*            (a) [ ]
                                                                         (b) [ ]

--------------------------------------------------------------------------------
3           SEC USE ONLY


--------------------------------------------------------------------------------
4           SOURCE OF FUNDS*


            OO
--------------------------------------------------------------------------------
5           CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) OR 2(e)                                               [ ]


--------------------------------------------------------------------------------
6           CITIZENSHIP OR PLACE OF ORGANIZATION


            Delaware
--------------------------------------------------------------------------------
                          7         SOLE VOTING POWER
       NUMBER OF
         SHARES
      BENEFICIALLY
        OWNED BY          ------------------------------------------------------
          EACH            8         SHARED VOTING POWER
       REPORTING
         PERSON
          WITH
                          ------------------------------------------------------
                          9         SOLE DISPOSITIVE POWER


                          ------------------------------------------------------
                          10        SHARED DISPOSITIVE POWER


--------------------------------------------------------------------------------
11          AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON


            12,954,328
--------------------------------------------------------------------------------
12          CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES*                                                          [ ]


--------------------------------------------------------------------------------
13          PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)


            22.17%
--------------------------------------------------------------------------------
14          TYPE OF REPORTING PERSON*


            OO
--------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!

--------------------------------------------------------------------------------
1           NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)


            REIT Management & Research Trust  I.R.S. ID No. 04-3402206
--------------------------------------------------------------------------------
2           CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*            (a) [ ]
                                                                         (b) [ ]

--------------------------------------------------------------------------------
3           SEC USE ONLY


--------------------------------------------------------------------------------
4           SOURCE OF FUNDS*


            OO
--------------------------------------------------------------------------------
5           CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) OR 2(e)                                               [ ]


--------------------------------------------------------------------------------
6           CITIZENSHIP OR PLACE OF ORGANIZATION


            Massachusetts
--------------------------------------------------------------------------------
                          7         SOLE VOTING POWER
       NUMBER OF
         SHARES
      BENEFICIALLY
        OWNED BY          ------------------------------------------------------
          EACH            8         SHARED VOTING POWER
       REPORTING
         PERSON
          WITH
                          ------------------------------------------------------
                          9         SOLE DISPOSITIVE POWER



                          ------------------------------------------------------
                          10        SHARED DISPOSITIVE POWER


--------------------------------------------------------------------------------
11          AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON


            12,954,328
--------------------------------------------------------------------------------
12          CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES*                                                          [ ]


--------------------------------------------------------------------------------
13          PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)


            22.17%
--------------------------------------------------------------------------------
14          TYPE OF REPORTING PERSON*


            OO
--------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!


         This Amendment No. 4 to the original  Schedule 13D filed  September 29,
1999,  by HRPT  Properties  Trust and REIT  Management & Research,  Inc. and the
initial  Schedule 13D filed by REIT  Management & Research  Trust on October 23,
2001, is being filed to reflect a decrease in the reported percentage  ownership
of Senior Housing  Properties  Trust as described below and update certain other
information.

Item 1. Security and Issuer.

         The class of equity  securities to which this statement  relates is the
Common Shares of Beneficial Interest, par value $0.01 (the "Shares"),  of Senior
Housing Properties Trust, a Maryland real estate investment Trust ("SNH"),  with
its  principal   executive  offices  located  at  400  Centre  Street,   Newton,
Massachusetts 02458.

Item 2. Identity and Background.

         The persons filing this statement are HRPT Properties Trust, a Maryland
real estate investment trust ("HRP"), REIT Management & Research LLC, a Delaware
limited  liability  company  ("RMR"),  and REIT  Management & Research  Trust, a
Massachusetts business trust ("RMR Trust").

         HRP's  principal  business  is to operate as a real  estate  investment
trust.  The  principal  office of HRP is located at 400 Centre  Street,  Newton,
Massachusetts 02458. The trustees of HRP are Patrick F. Donelan,  Rev. Justinian
Manning, C.P., Frederick N. Zeytoonjian,  Barry M. Portnoy and Gerard M. Martin.
The executive officers of HRP are John A. Mannix,  President and Chief Operating
Officer,  John C. Popeo,  Treasurer,  Chief  Financial  Officer  and  Secretary,
Jennifer B. Clark,  Senior Vice  President and Assistant  Secretary and David M.
Lepore, Senior Vice President.

         RMR's principal  business is providing advisory services to real estate
investment trusts such as SNH and others. The principal office of RMR is located
at 400 Centre  Street,  Newton,  Massachusetts  02458.  The directors of RMR are
David J. Hegarty,  Gerard M. Martin and Barry M. Portnoy. The executive officers
of RMR are David J. Hegarty,  President and Secretary, John G. Murray, Executive
Vice  President,  Evrett W.  Benton,  Vice  President,  Jennifer B. Clark,  Vice
President and Assistant  Secretary,  David M. Lepore,  Vice  President,  John A.
Mannix,  Vice  President,  Thomas M.  O'Brien,  Vice  President,  John C. Popeo,
Treasurer,  John R.  Hoadley,  Vice  President  and Bruce J. Mackey,  Jr.,  Vice
President. The sole member and manager of RMR is RMR Trust.

         RMR Trust's  principal  business is to act as the member and manager of
RMR. The principal office of RMR Trust is located at 400 Centre Street,  Newton,
Massachusetts  02458. The trustees and  executive  officers of RMR Trust
are the same as the  directors  and  executive  officers of RMR. Each of Messrs.
Martin and Portnoy own 50% of the outstanding capital stock of RMR Trust.

         Each of the individuals  listed above (i) except for Mr. Donelan,  is a
United  Stated  citizen,  (ii)  except for Mr.  Donelan,  Rev.  Manning  and Mr.
Zeytoonjian,  has a business address at 400 Centre Street, Newton, Massachusetts
02458 and (iii) except for Mr. Donelan,  Rev.  Manning,  and Mr.  Zeytoonjian is
principally employed by RMR, in the capacities specified above. Mr. Hegarty also
serves as President,  Chief Operating Officer,  and Secretary of SNH and John R.
Hoadley  also  serves as  Treasurer  and Chief  Financial  Officer  of SNH.  The
principal office of SNH is located at 400 Centre Street,  Newton,  Massachusetts
02458.  Mr.  Donelan is a British  citizen and is Chairman  and Chief  Executive
Officer of  eSecLending  and has a business  address at Sion Hall,  56  Victoria
Embankment,  London, United Kingdom. Rev. Manning is the pastor of St. Gabriel's
parish at 139 Washington Street, Brighton,  Massachusetts 02135. Mr. Zeytoonjian
is Chairman and Chief Executive  Officer of Turf Products  Corporation and has a
business address at 157 Moody Road, Enfield, Connecticut 06083.

         Neither HRP, RMR, RMR Trust nor any of the individuals  specified above
has,  during  the last five  years,  been  convicted  in a  criminal  proceeding
(excluding  traffic  violations or similar  misdemeanors),  or been party to any
civil proceeding  which resulted in a judgment,  decree or final order enjoining
future violations of, or prohibiting or mandating activities subject to, federal
or state securities laws or finding any violation with respect to such laws.


Item 5. Interest in securities of the issuer.

         (a) On  February  20,  2002,  SNH  issued an  aggregate  of  15,000,000
additional  Shares in an  underwritten  public  offering.  HRP continues to hold
12,809,238  Shares,  which as a result of SNH's  offering  of  Shares  represent
21.93% of the issued and outstanding Shares.

         In addition, the trustees,  directors and executive officers of HRP own
SNH Shares as follows: Mr. Martin,  through a corporation of which Mr. Martin is
the sole stockholder, 61,204 Shares; Mr. Portnoy, through a corporation of which
Mr.  Portnoy is the sole  stockholder,  61,204  Shares;  and other  trustees and
executive officers of HRP, 5,897 Shares in the aggregate.  In addition,  Messrs.
Portnoy  and  Martin,  as  Managing  Trustees  of  HRP,  may be  deemed  to have
beneficial  ownership of the  12,809,238  Shares held by HRP;  however,  Messrs.
Portnoy and Martin disclaim beneficial ownership of HRP's 12,809,238 Shares. The
Shares held by HRP,  when  aggregated  with such  additional  Shares held by the
trustees,  directors and executive officers of HRP, aggregate 12,937,493 Shares,
which represent 22.14% of the issued and outstanding  Shares. The Shares held by
Mr. Martin, Mr. Portnoy and the other trustees and executive officers of HRP are
reported  herein  pursuant to the  provisions  of Items 2 and 5 of Schedule 13D.
HRP, however, expressly disclaims any beneficial ownership of the Shares held by
Mr. Martin, Mr. Portnoy and the other trustees and executive officers of HRP.

         RMR, as HRP's advisor, and RMR Trust, as the sole member and manager of
RMR, may under applicable regulatory definitions,  be deemed to beneficially own
HRP's 12,809,238  Shares.  RMR and RMR Trust,  however,  expressly  disclaim any
beneficial ownership of HRP's 12,809,238 Shares.

         In addition,  the trustees and executive  officers of RMR and RMR Trust
own SNH  Shares  as  follows,  in part as noted  above:  Mr.  Martin,  through a
corporation  of which Mr. Martin is the sole  stockholder,  61,204  Shares;  Mr.
Portnoy,  through a corporation  of which Mr.  Portnoy is the sole  stockholder,
61,204 Shares;  Mr. Hegarty,  8,670 Shares;  and other executive officers of RMR
Trust,  14,012  Shares in the  aggregate.  The Shares  held by HRP (which may be
deemed to be beneficially owned by RMR and RMR Trust), when aggregated with such
additional  Shares held by the  trustees  and  executive  officers of RMR Trust,
aggregate   12,954,328  Shares,   which  represent  22.17%  of  the  issued  and
outstanding Shares. The Shares held by Mr. Martin, Mr. Portnoy,  Mr. Hegarty and
the other  executive  officers of RMR and RMR Trust are reported herein pursuant
to the provisions of Items 2 and 5 of Schedule 13D. RMR and RMR Trust,  however,
expressly  disclaims any beneficial  ownership of the Shares held by Mr. Martin,
Mr. Portnoy, Mr. Hegarty and the other executive officers of RMR Trust.

         (b) HRP has sole power to vote or dispose of its 12,809,238  Shares. To
HRP's knowledge, each of the trustees,  directors and executive officers of HRP,
RMR and RMR Trust  described  above  has sole  power to vote or  dispose  of the
Shares he or she beneficially owns.

         (c) No  transactions in Shares have been effected during the past sixty
days by HRP, RMR, RMR Trust or the trustees, directors and executive officers of
HRP, RMR and RMR Trust described above.

         (d) No other  person is known to have the right to receive or the power
to direct the receipt of  distributions  from,  or the proceeds from the sale of
securities covered by this statement.


Item 7.  Material to be Filed as Exhibits.

The following documents are filed as exhibits to this statement:

1.       Joint Filing Agreement, dated as of October 23, 2001, by and
between HRP, RMR and RMR Trust.*

--------------
*        Incorporated by reference to the filing persons' Schedule 13D/A with
         respect to the securities of SNH filed October 23, 2001.




                                    SIGNATURE


         After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

March 4, 2002                    HRPT PROPERTIES TRUST


                                     By: /s/ John Popeo
                                         John Popeo
                                         Treasurer and Chief Financial Officer


                                     REIT MANAGEMENT & RESEARCH LLC



                                     By: /s/ Jennifer B. Clark
                                         Jennifer B. Clark
                                         Vice President and Assistant Secretary

                                     REIT MANAGEMENT & RESEARCH TRUST


                                     By: /s/ Thomas M. O'Brien
                                         Thomas M. O'Brien
                                         Vice President