Document:

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                                   EXHIBIT 4.1

                                                                  EXECUTION COPY

                          SUPPLEMENTAL INDENTURE NO. 1

                                 BY AND BETWEEN

                         SENIOR HOUSING PROPERTIES TRUST

                                       AND

                       STATE STREET BANK AND TRUST COMPANY

                             AS OF DECEMBER 20, 2001

           SUPPLEMENTAL TO THE INDENTURE DATED AS OF DECEMBER 20, 2001

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

                         SENIOR HOUSING PROPERTIES TRUST

                          8-5/8% SENIOR NOTES DUE 2012

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     This SUPPLEMENTAL INDENTURE NO. 1 (this "SUPPLEMENTAL INDENTURE") made and
entered into as of December 20, 2001 between SENIOR HOUSING PROPERTIES TRUST, a
Maryland real estate investment trust (the "COMPANY"), and STATE STREET BANK AND
TRUST COMPANY, a Massachusetts trust company, as Trustee (the "TRUSTEE"),

                                WITNESSETH THAT:

     WHEREAS, the Company and the Trustee have executed and delivered an
Indenture, dated as of December 20, 2001 (as amended, supplemented or otherwise
modified from time to time, the "BASE INDENTURE" and, together with this
Supplemental Indenture, as amended, supplemented or otherwise modified from time
to time, the "INDENTURE") to provide for the future issuance of the Company's
senior debt securities (the "SECURITIES") to be issued from time to time in one
or more series; and

     WHEREAS, pursuant to the terms of the Base Indenture, the Company desires
to provide for the establishment of a series of its Securities, to be known as
its 8-5/8% Senior Notes due 2012, the form and substance of such Securities and
the terms, provisions and conditions thereof to be set forth as provided in the
Indenture;

             NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH:

                                    ARTICLE 1

                                  DEFINED TERMS

     SECTION 1.1 The following definitions supplement, and, to the extent
inconsistent with, replace the definitions in Section 101 of the Base Indenture:

     "ACQUIRED DEBT" means Debt of a Person (i) existing at the time such Person
becomes a Subsidiary or (ii) assumed in connection with the acquisition of
assets from such Person, in each case, other than Debt incurred in connection
with, or in contemplation of, such Person becoming a Subsidiary or such
acquisition. Acquired Debt shall be deemed to be incurred on the date of the
related acquisition of assets from any Person or the date the acquired Person
becomes a Subsidiary.

     "ADJUSTED TOTAL ASSETS" is defined in clause (i) of Section 3.1(a).

     "ANNUAL DEBT SERVICE" as of any date means the maximum amount which is
expensed in any 12-month period for interest on Debt of the Company and its
Subsidiaries excluding amortization of debt discount and deferred financing
costs.

     "BUSINESS DAY" means any day other than a Saturday or Sunday or a day on
which banking institutions in the City of New York are required or authorized to
close.

     "CAPITAL STOCK" means, with respect to any Person, any capital stock
(including preferred stock), shares, interests, participation or other ownership
interests (however designated) of such

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Person and any rights (other than debt securities convertible into or
exchangeable for capital stock), warrants or options to purchase any thereof.

     "CASH EQUIVALENTS" means:

          (i) demand deposits, certificates of deposit or repurchase agreements
     issued by or maintained with banks or other financial institutions;

          (ii) marketable securities issued or directly and fully guaranteed as
     to timely payment by the United States of America or any agency or
     instrumentality thereof, or

          (iii) any commercial paper or other obligation rated, at time of
     purchase, at least "P-2" (or its equivalent) by Moody's or at least "A-2"
     (or its equivalent) by Standard & Poor's.

     "CHANGE OF CONTROL" means such time as any "person" or "group" (as such
terms are defined in Sections 13(d) and 14(d)(2) of the Exchange Act), other
than an Excluded Person, becomes the "beneficial owner" (as defined in Rule
13d-3 under the Exchange Act) of more than 50% of the total voting power of the
Voting Stock of the Company on a fully diluted basis. For such purpose,
"EXCLUDED PERSON" means (i) RMR, HRPT Properties Trust, a Maryland real estate
investment trust, Hospitality Properties Trust, a Maryland real estate
investment trust, or any other entity for which financing, investment and
operating oversight for substantially all of such entity's activities is
provided by RMR, or any successor to or affiliate of such persons, and (ii) any
person or group acquiring shares issued by the Company in connection with a
merger or acquisition, if the person or group has agreed with the Company to
distribute such shares to the holders of its or their securities within a period
of not longer than one year from the date of such agreement (the "Distribution
Period") and, giving pro forma effect to such distribution as of the date on
which the agreement for the merger or acquisition was entered into (and giving
effect to the transactions contemplated by that agreement), no Change of Control
would have occurred; PROVIDED that if such distribution does not occur by the
end of the Distribution Period, a Change in Control shall be deemed to have
occurred at the end of the Distribution Period.

     "CHANGE OF CONTROL OFFER" is defined in Section 4.1 of this Supplemental
Indenture.

     "CHANGE OF CONTROL PAYMENT" is defined in Section 4.1 of this Supplemental
Indenture.

     "CHANGE OF CONTROL PAYMENT DATE" is defined in Section 4.1 of this
Supplemental Indenture.

     "CONSOLIDATED INCOME AVAILABLE FOR DEBT SERVICE" for any period means
Earnings from Operations of the Company and its Subsidiaries plus amounts which
have been deducted, and minus amounts which have been added, for the following
(without duplication): (i) interest or distributions on Debt of the Company and
its Subsidiaries, (ii) provision for taxes of the Company and its Subsidiaries
based on income, (iii) amortization

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of debt discount and deferred financing costs, (iv) provisions for gains and
losses on properties and property depreciation and amortization, (v) the effect
of any noncash charge resulting from a change in accounting principles in
determining Earnings from Operations for such period and (vi) amortization of
deferred charges.

     "DEBT" of the Company or any Subsidiary means, without duplication, any
indebtedness of the Company or any Subsidiary, whether or not contingent, in
respect of (i) borrowed money or evidenced by bonds, notes, debentures or
similar instruments, (ii) indebtedness for borrowed money secured by any
Encumbrance existing on property owned by the Company or any Subsidiary, to the
extent of the lesser of (x) the amount of indebtedness so secured or (y) the
fair market value of the property subject to such Encumbrance, (iii) the
reimbursement obligations, contingent or otherwise, in connection with any
letters of credit actually issued (other than letters of credit issued to
provide credit enhancement or support with respect to other indebtedness of the
Company or any Subsidiary otherwise reflected as Debt hereunder) or amounts
representing the balance deferred and unpaid of the purchase price of any
property or services, except any such balance that constitutes an accrued
expense, trade payable, conditional sale obligations or obligations under any
title retention agreement, (iv) the principal amount of all obligations of the
Company or any Subsidiary with respect to redemption, repayment or other
repurchase of any Disqualified Stock, or (v) any lease of property by the
Company or any Subsidiary as lessee which is reflected on the Company's
consolidated balance sheet as a capitalized lease in accordance with GAAP, to
the extent, in the case of items of indebtedness under (i) through (iii) above,
that any such items (other than letters of credit) would appear as a liability
on the Company's consolidated balance sheet in accordance with GAAP. Debt also
includes, to the extent not otherwise included, any obligation by the Company or
any Subsidiary to be liable for, or to pay, as obligor, guarantor or otherwise
(other than for purposes of collection in the ordinary course of business), Debt
of another Person (other than the Company or any Subsidiary); it being
understood that Debt shall be deemed to be incurred by the Company or any
Subsidiary whenever the Company or such Subsidiary shall create, assume,
guarantee or otherwise become liable in respect thereof.

     "DISQUALIFIED STOCK" means, with respect to any Person, any Capital Stock
of such Person which by the terms of such Capital Stock (or by the terms of any
security into which it is convertible or for which it is exchangeable or
exercisable), upon the happening of any event or otherwise (other than pursuant
to a change of control provision not materially more favorable to the holder
thereof than that set forth in Section 4.1 of this Supplemental Indenture), (i)
matures or is mandatorily redeemable, pursuant to a sinking fund obligation or
otherwise (other than Capital Stock which is redeemable solely in exchange for
Capital Stock which is not Disqualified Stock or for Subordinated Debt), (ii) is
convertible into or exchangeable or exercisable for Debt, other than
Subordinated Debt or Disqualified Stock, or (iii) is redeemable at the option of
the holder thereof, in whole or in part (other than Capital Stock which is
redeemable solely in exchange for Capital Stock which is not Disqualified Stock
or for Subordinated Debt); in each case on or prior to the Stated Maturity of
the principal of the Notes.

     "EARNINGS FROM OPERATIONS" for any period means net earnings excluding
gains and losses on sales of investments, extraordinary items, distributions on
equity securities and property valuation losses, as reflected in the financial
statements of the Company and its Subsidiaries for such period, determined on a
consolidated basis in accordance with GAAP.

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     "ENCUMBRANCE" means any mortgage, lien, charge, pledge, security interest
or other encumbrance of any kind.

     "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended.

     "EXCLUDED REFUNDING" means, at any time, any voluntary or optional
principal payment, or voluntary or optional redemption, repurchase, defeasance,
or other acquisition or retirement for value, of Subordinated Debt of the
Company or any Subsidiary in an amount not exceeding the aggregate Net Cash
Proceeds received by the Company and its Subsidiaries from the substantially
concurrent sale of Qualified Subordinated Debt, to the extent such proceeds have
not theretofore been taken in account in calculating the amount of an Excluded
Refunding. For such purpose, "QUALIFIED SUBORDINATED DEBT" means Subordinated
Debt of the Company or a Subsidiary of the Company (or trust preferred
securities or similar Capital Stock of a Subsidiary of the Company as to which
any related Debt of the Company or other Subsidiaries of the Company is
Subordinated Debt) which does not mature and is not subject to mandatory
repurchase or redemption or to repurchase or redemption at the option of the
holder thereof (other than pursuant to a change of control provision not
materially more favorable to the holder thereof than that set forth in Section
4.1 of this Supplemental Indenture) in whole or in part prior to the Stated
Maturity of the principal of the Notes.

     "FUNDS FROM OPERATIONS" for any period means Earnings from Operations for
such period plus amounts which have been deducted, and minus amounts that have
been added, for the following (without duplication): (i) provision for taxes of
the Company and its Subsidiaries based on income, (ii) amortization of debt
discount and deferred financing costs, (iii) provisions for gains and losses on
properties and property depreciation and amortization, (iv) the effect of any
noncash charge resulting from a change in accounting principles in determining
Earnings from Operations for such period, (v) expenses and charges relating to
the spin-off of Five Star Quality Care, Inc., and (vi) amortization of deferred
charges.

     "INTEREST PAYMENT DATE" with respect to the Notes is defined in Section 101
of the Base Indenture and Section 2.1(b) of this Supplemental Indenture.

     "MAKE-WHOLE AMOUNT" means, in connection with any optional redemption or
accelerated payment of the Notes, the excess, if any, of:

          (i) the aggregate present value as of the date of such redemption or
     accelerated payment of each dollar of principal being redeemed or paid and
     the amount of interest (exclusive of interest accrued to the date of
     redemption or accelerated payment) that would have been payable in respect
     of each such dollar if such redemption or accelerated payment had not been
     made, determined by discounting, on a semi-annual basis, such principal and
     interest at the Reinvestment Rate (determined on the third Business Day
     preceding the date a notice of redemption is given or declaration of
     acceleration is made) from the respective dates on which such principal and
     interest would have been payable if such redemption or payment had not been
     made, over

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          (ii) the aggregate Outstanding principal amount of the Notes being
     redeemed or paid.

     "MOODY'S" means Moody's Investors Services, Inc. or any successor thereof.

     "NET CASH PROCEEDS" means the proceeds of any issuance or sale of Capital
Stock, in the form of cash or Cash Equivalents, including payments in respect of
deferred payment obligations when received in the form of, or shares or other
assets when disposed for, cash or Cash Equivalents (except to the extent that
such obligations are financed or sold with recourse to the Company or any
Subsidiary), net of attorney's fees, accountant's fees and brokerage,
consultation, underwriting and other fees and expenses actually incurred in
connection with such issuance or sale and net of taxes paid or payable as a
result thereof.

     "NOTES" means the Company's 8-5/8% Senior Notes due 2012, issued under the
Indenture.

     "REGULAR RECORD DATE" with respect to the Notes is defined in Section 101
of the Base Indenture and Section 2.1(b) of this Supplemental Indenture.

     "REINVESTMENT RATE" means 0.50% plus the arithmetic mean of the yields
under the respective heading Week Ending published in the most recent
Statistical Release under the caption Treasury Constant Maturities for the
maturity (rounded to the nearest month) corresponding to the remaining life to
Stated Maturity, as of the date of the principal being redeemed or paid. If no
maturity exactly corresponds to such Stated Maturity, yields for the two
published maturities most closely corresponding to such Stated Maturity shall be
calculated pursuant to the immediately preceding sentence and the Reinvestment
Rate shall be interpolated or extrapolated from such yields on a straight-line
basis, rounding in each of such relevant periods to the nearest month. For the
purpose of calculating the Reinvestment Rate, the most recent Statistical
Release published prior to the date of determination of the Make-Whole Amount
shall be used.

     "RMR" means Reit Management & Research LLC, a Delaware limited liability
company.

     "SECURED DEBT" means Debt secured by any Encumbrance.

     "STANDARD & POOR'S" means Standard & Poor's Rating Services, a division of
The McGraw-Hill Companies, Inc. or any successor thereof.

     "STATISTICAL RELEASE" means that statistical release designated H.15(519)
or any successor publication that is published weekly by the Federal Reserve
System and that establishes annual yields on actively traded United States
government securities adjusted to constant maturities, or, if such statistical
release is not published at the time of any determination under the Indenture,
then such other reasonably comparable index we designate.

     "SUBORDINATED DEBT" means Debt which by the terms of such Debt is
subordinated in right of payment to the principal of and interest and premium,
if any, on the Notes.

     "SUBSIDIARY" means any corporation or other entity of which a majority of
(i) the voting power of the voting equity securities or (ii) the outstanding
equity interests of which are owned,

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directly or indirectly, by the Company or one or more other Subsidiaries of the
Company. For the purposes of this definition, "voting equity securities" means
equity securities having voting power for the election of directors or similar
functionaries, whether at all times or only so long as no senior class of
security has such voting power by reason of any contingency.

     "TOTAL ASSETS" as of any date means the sum of (i) the Undepreciated Real
Estate Assets and (ii) all other assets of the Company and its Subsidiaries
determined in accordance with GAAP (but excluding accounts receivable and
intangibles).

     "TOTAL UNENCUMBERED ASSETS" means the sum of (i) the Undepreciated Real
Estate Assets of the Company and its Subsidiaries not securing any portion of
Secured Debt and (ii) all other assets, including accounts receivable and
intangibles, of the Company and its Subsidiaries not securing any portion of
Secured Debt determined on a consolidated basis in accordance with GAAP. If
Secured Debt secured by real estate or other property or assets of the Company
or its Subsidiaries ("Secondary Collateral") is fully defeased in accordance
with the terms thereof or is also secured by cash or Cash Equivalents in an
amount (determined at the lesser of (i) carrying value in accordance with GAAP
or (ii) fair market value) at least equal to the outstanding principal amount of
such Secured Debt, such Secondary Collateral shall be deemed not to secure any
portion of such Secured Debt for purposes of this definition.

     "UNDEPRECIATED REAL ESTATE ASSETS" as of any date means the cost (original
cost plus capital improvements less adjustments to carrying value in accordance
with GAAP made prior to January 1, 2001) of real estate and associated tangible
personal property used in connection with the real estate assets of the Company
and its Subsidiaries on such date, before depreciation and amortization
determined on a consolidated basis in accordance with GAAP.

     "UNSECURED DEBT" means any Debt which is not Secured Debt.

     "VOTING STOCK" of any Person means the Capital Stock of such Person that is
at the time entitled to vote in the election of the board of directors, board of
trustees or the equivalent of such Person.

                                    ARTICLE 2

                               TERMS OF THE NOTES

     SECTION 2.1 Pursuant to Section 301 of the Indenture, the Notes shall have
the following terms and conditions:

     (a) TITLE; AGGREGATE PRINCIPAL AMOUNT; FORM OF NOTES. The Notes shall be
Registered Securities under the Indenture and shall be known as the Company's
"8-5/8% Senior Notes due 2012." The Notes will be limited to an aggregate
principal amount of $200,000,000, subject to the right of the Company to reopen
such series for issuances of additional securities of such series and except (i)
as provided in this Section and (ii) for Securities authenticated and delivered
upon registration of transfer of, or in exchange for, or in lieu of, other
Securities of the series pursuant to Section 304, 305, 306, 906 or 1107 of the
Indenture and except for any Securities which, pursuant to Section 303 of the
Indenture, are deemed never to have been authenticated

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and delivered hereunder. The Notes (together with the Trustee's certificate of
authentication) shall be substantially in the form of Exhibit A hereto, which is
hereby incorporated in and made a part of this Supplemental Indenture.

     The Notes will be issued in the form of one or more registered global
securities without coupons ("Global Notes") that will be deposited with, or on
behalf of, The Depository Trust Company ("DTC"), and registered in the name of
DTC's nominee, Cede & Co. Except under the circumstance described below, the
Notes will not be issuable in definitive form. Unless and until it is exchanged
in whole or in part for the individual notes represented thereby, a Global Note
may not be transferred except as a whole by DTC to a nominee of DTC or by a
nominee of DTC to DTC or another nominee of DTC or by DTC or any nominee of DTC
to a successor depositary or any nominee of such successor.

     So long as DTC or its nominee is the registered owner of a Global Note, DTC
or such nominee, as the case may be, will be considered the sole owner or holder
of the Notes represented by such Global Note for all purposes under this
Supplemental Indenture. Except as described below, owners of beneficial interest
in Notes evidenced by a Global Note will not be entitled to have any of the
individual Notes represented by such Global Note registered in their names, will
not receive or be entitled to receive physical delivery of any such Notes in
definitive form and will not be considered the owners or holders thereof under
the Indenture or this Supplemental Indenture.

     If DTC is at any time unwilling, unable or ineligible to continue as
depositary and a successor depositary is not appointed by the Company within 90
days, the Company will issue individual Notes in exchange for the Global Note or
Global Notes representing such Notes. In addition, the Company may at any time
and in its sole discretion, subject to certain limitations set forth in the
Indenture, determine not to have any of such Notes represented by one or more
Global Notes and, in such event, will issue individual Notes in exchange for the
Global Note or Global Notes representing the Notes. Individual Notes so issued
will be issued in denominations of $1,000 and integral multiples thereof.

     (b) INTEREST AND INTEREST RATE. The Notes will bear interest at a rate of
8-5/8% per annum, from December 20, 2001 (or, in the case of Notes issued upon
the reopening of this series of Notes, from the date designated by the Company
in connection with such reopening) or from the immediately preceding Interest
Payment Date to which interest has been paid or duly provided for, payable
semiannually on each January 15 and July 15, commencing July 15, 2002 (each of
which shall be an "Interest Payment Date"), to the Persons in whose names the
Notes are registered in the Security Register at the close of business on
January 1 and July 1, as the case may be (whether or not a Business Day), next
preceding such Interest Payment Date (each, a "Regular Record Date").

     (c) PRINCIPAL REPAYMENT; CURRENCY. The Stated Maturity of the principal of
the Notes is January 15, 2012, PROVIDED, HOWEVER, the Notes may be earlier
redeemed at the option of the Company as provided in paragraph (d) below. The
principal of each Note payable at its Stated Maturity shall be paid against
presentation and surrender thereof at the Corporate Trust Office of the Trustee,
located initially at Two Avenue de Lafayette, Boston, Massachusetts 02111, in
such

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coin or currency of the United States of America as at the time of payment is
legal tender for the payment of public or private debts.

     (d) REDEMPTION AT THE OPTION OF THE COMPANY. The Notes will be subject to
redemption at any time at the option of the Company, in whole or in part, upon
not less than 30 nor more than 60 days' notice to each Holder of Notes to be
redeemed at its address appearing in the Security Register, at a price equal to
the sum of (i) the Outstanding principal amount of the Notes being redeemed,
plus accrued and unpaid interest to but excluding the applicable Redemption
Date, plus (ii) the Make-Whole Amount, if any.

     (e) NOTICES. All notices and other communications hereunder shall be in
writing and shall be deemed to have been duly given if mailed or transmitted by
any standard form of telecommunication. Notices to the Company shall be directed
to it at 400 Centre Street, Newton, Massachusetts 02458, Attention: President;
notices to the Trustee shall be directed to it at Two Avenue de Lafayette,
Boston, Massachusetts 02111, Attention: Corporate Trust Department, Re: Senior
Housing Properties Trust 8-5/8% Senior Notes due 2012; or as to either party, at
such other address as shall be designated by such party in a written notice to
the other party.

     (f) GLOBAL NOTE LEGEND. Each Global Note shall bear the following legend on
the face thereof:

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
         THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO ISSUER
         OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT, AND
         ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN
         SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC
         (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS
         REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER,
         PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON
         IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
         INTEREST HEREIN.

     (g) APPLICABILITY OF DISCHARGE, DEFEASANCE AND COVENANT DEFEASANCE
PROVISIONS. The Discharge, Defeasance and Covenant Defeasance provisions in
Article Thirteen of the Indenture will apply to the Notes.

                                    ARTICLE 3

                              ADDITIONAL COVENANTS

     SECTION 3.1 Holders of the Notes shall have the benefit of the following
covenants, in addition to the covenants of the Company set forth in Article
Eight of the Indenture:

     (a) LIMITATIONS ON INCURRENCE OF DEBT.

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          (i) The Company will not, and will not permit any Subsidiary to, incur
     any Debt if, immediately after giving effect to the incurrence of such
     additional Debt and the application of the proceeds thereof, the aggregate
     principal amount of all outstanding Debt of the Company and its
     Subsidiaries on a consolidated basis determined in accordance with GAAP is
     greater than 60% of the sum ("Adjusted Total Assets") of (without
     duplication) (A) the Total Assets of the Company and its Subsidiaries as of
     the end of the calendar quarter covered in the Company's Annual Report on
     Form 10-K, or Quarterly Report on Form 10-Q, as the case may be, most
     recently filed with the Securities and Exchange Commission (or, if such
     filing is not permitted under the Exchange Act with the Trustee) prior to
     the incurrence of such additional Debt and (B) the purchase price of any
     real estate assets or mortgages receivable acquired, and the amount of any
     securities offering proceeds received (to the extent that such proceeds
     were not used to acquire real estate assets or mortgages receivable or used
     to reduce Debt), by the Company or any Subsidiary since the end of such
     calendar quarter, including those proceeds obtained in connection with the
     incurrence of such additional Debt.

          (ii) The Company will not, and will not permit any Subsidiary to,
     incur any Secured Debt if, immediately after giving effect to the
     incurrence of such additional Secured Debt and the application of the
     proceeds thereof, the aggregate principal amount of all outstanding Secured
     Debt of the Company and its Subsidiaries on a consolidated basis is greater
     than 40% of Adjusted Total Assets.

          (iii) The Company will not, and will not permit any Subsidiary to,
     incur any Debt if the ratio of Consolidated Income Available for Debt
     Service to the Annual Debt Service for the four consecutive fiscal quarters
     most recently ended prior to the date on which such additional Debt is to
     be incurred shall have been less than 2.0 to 1.0, on a pro forma basis
     after giving effect thereto and to the application of the proceeds
     therefrom, and calculated on the assumption that (A) such Debt and any
     other Debt incurred by the Company and its Subsidiaries on a consolidated
     basis since the first day of such four-quarter period and the application
     of the proceeds therefrom, including to refinance other Debt, had occurred
     at the beginning of such period; (B) the repayment or retirement of any
     other Debt by the Company and its Subsidiaries since the first date of such
     four-quarter period had been repaid or retired at the beginning of such
     period (except that, in making such computation, the amount of Debt under
     any revolving credit facility shall be computed based upon the average
     daily balance of such Debt during such period); (C) in the case of Acquired
     Debt or Debt incurred in connection with any acquisition since the first
     day of such four-quarter period, the related acquisition had occurred as of
     the first day of such period with appropriate adjustments with respect to
     such acquisition being included in such pro forma calculation; and (D) in
     the case of any acquisition or disposition by the Company or its
     Subsidiaries on a consolidated basis of any asset or group of assets since
     the first day of such four-quarter period, whether by merger, stock
     purchase or sale, or asset purchase or sale, such acquisition or
     disposition or any related repayment of Debt had occurred as of the first
     day of such period with the appropriate adjustments with respect to such
     acquisition or disposition being included in such pro forma calculation. If
     the Debt giving rise to the need to make the foregoing calculation or any
     other Debt incurred after the first day of the relevant four-quarter period
     bears

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     interest at a floating rate then, for purposes of calculating the Annual
     Debt Service, the interest rate on such Debt shall be computed on a pro
     forma basis as if the average interest rate which would have been in effect
     during the entire such four-quarter period had been the applicable rate for
     the entire such period.

     (b) LIMITATIONS ON DISTRIBUTIONS. The Company will not, and will not permit
any Subsidiary to, (i) declare or pay any dividend or make any distribution on
or with respect to the Company's Capital Stock (other than (x) dividends or
distributions payable solely in shares of the Company's Capital Stock, other
than Disqualified Stock, or in options, warrants or other rights to acquire
shares of such Capital Stock and (y) the spin-off distribution of the Capital
Stock of Five Star Quality Care, Inc.); (ii) purchase, redeem, retire or
otherwise acquire for value any shares of the Company's Capital Stock; or (iii)
make any voluntary or optional principal payment, or voluntary or optional
redemption, repurchase, defeasance, or other acquisition or retirement for
value, of Subordinated Debt (other than Excluded Refundings); unless,
immediately after giving pro forma effect to such distribution (each, a
"Restricted Payment"):

     (A)  no Default under the Indenture shall have occurred and be continuing
          or would occur as a result of such Restricted Payment;

     (B)  the Company and its Subsidiaries would have been permitted to incur at
          least $1.00 of additional Debt (other than Debt between the Company
          and one or more its Subsidiaries or between one or more its
          Subsidiaries) under the terms of Section 3.1(a) of this Supplemental
          Indenture; and

     (C)  the aggregate amount of all Restricted Payments (the amount, if other
          than in cash, to be determined in good faith by the Board, whose
          determination shall be conclusive and evidenced by a Board Resolution)
          made after the date of this Supplemental Indenture would not exceed
          the sum of:

          (I)  95% of Funds from Operations accrued on a cumulative basis during
               the period (taken as one accounting period) beginning on October
               1, 2001 and ending on the last day of the Company's most recently
               completed calendar quarter; plus

          (II) 100% of the aggregate Net Cash Proceeds received by the Company
               after the date of this Supplemental Indenture from the issuance
               or sale of Capital Stock of the Company to a Person which is not
               a Subsidiary of the Company; plus

          (III) $15,000,000.

Notwithstanding the foregoing, this Section 3.1(b) shall not prohibit or limit,
and shall not be violated by, (i) any dividend, distribution or other action
which is necessary to distribute 100% of the Company's real estate investment
trust taxable income (determined prior to any deductions for dividends paid) or
to maintain the Company's status as a real estate investment trust under the
Internal Revenue Code of 1986, as amended, if the aggregate principal amount of
all outstanding Debt of the Company and its Subsidiaries on a consolidated basis
determined in

                                      -10-
<PAGE>

accordance with GAAP is less than 60% of Adjusted Total Assets, or (ii) the
payment of any dividend or other distribution within 60 days of the declaration
thereof if at the date of declaration thereof such payment would have complied
with the provisions of this Section 3.1(b).

     (c) MAINTENANCE OF TOTAL UNENCUMBERED ASSETS. The Company and its
Subsidiaries will maintain at all times Total Unencumbered Assets of not less
than 150% of the aggregate outstanding principal amount of the Unsecured Debt of
the Company and its Subsidiaries on a consolidated basis in accordance with
GAAP.

     (d) COMPANY MAY CONSOLIDATE, ETC., ONLY ON CERTAIN TERMS. In addition to
the provisions of Section 801 of the Indenture, the Company shall not
consolidate with or merge into any other Person or convey, transfer or lease its
properties and assets substantially as an entirety to any Person, and the
Company shall not permit any Person to consolidate with or merge into the
Company or convey, transfer or lease its properties and assets substantially as
an entirety to the Company, unless immediately after giving effect to such
transaction, the Person formed by such consolidation or into which the Company
is merged or the Person which acquires by conveyance or transfer, or which
leases, the properties and assets of the Company substantially as an entirety
would be permitted to incur at least $1.00 of additional Debt (other than Debt
between such Person and one or more of its Subsidiaries or between one or more
or its Subsidiaries) under the terms of Section 3.1(a) of this Supplemental
Indenture.

                                    ARTICLE 4

                   OFFER TO REPURCHASE UPON CHANGE OF CONTROL

     SECTION 4.1 Subject to Section 4.2, if a Change of Control occurs, the
Company shall make an offer (a "CHANGE OF CONTROL OFFER") to each Holder of the
Notes to repurchase all or any part (equal to $1,000 or an integral multiple
thereof) of such Holder's Notes at a purchase price, in cash, equal to 101% of
the aggregate outstanding principal amount of the Notes repurchased, plus
accrued and unpaid interest thereon, if any (subject to the right of Holders on
the relevant record date to receive interest due on the relevant interest
payment date), to the date of purchase (the "CHANGE OF CONTROL PAYMENT").

     Within 10 days following any Change of Control, the Company shall mail a
written offer (an "Offer") to each Holder in accordance with the terms of
Section 1104 of the Base Indenture. The Offer shall contain all the information
required by applicable law to be included therein. The Offer shall also contain
information concerning the business of the Company and its Subsidiaries which
the Company in good faith believes will enable such Holders to make an informed
decision with respect to the Change of Control Offer. The Offer shall contain
all instructions and materials necessary to enable such Holders to tender Notes
pursuant to the Change of Control Offer. The Offer shall also state:

     (a) that the Change of Control Offer is being made pursuant to this
covenant and that all Notes tendered will be accepted for payment on the Change
of Control Payment Date, as defined below;

                                      -11-
<PAGE>

     (b) the purchase price and the purchase date, which shall be no earlier
than 30 days and no later than 60 days from the date such notice is mailed (the
"CHANGE OF CONTROL PAYMENT DATE"), which date shall also be the date the Offer
expires;

     (c) that any Note not tendered will continue to accrue interest;

     (d) that, unless the Company defaults in the payment of the Change of
Control Payment, all Notes accepted for payment pursuant to the Change of
Control Offer shall cease to accrue interest after the Change of Control Payment
Date;

     (e) that Holders electing to have any Notes purchased pursuant to a Change
of Control Offer will be required to surrender the Notes, with the form entitled
"Option of Holder to Elect Purchase" on the reverse of the Notes completed, to
the Paying Agent at the address specified in the notice prior to close of
business on the date specified in such notice, which shall not be earlier than
first to occur of (i) the thirtieth day following the date of such notice and
(ii) the third Business Day preceding the Change of Control Payment Date;

     (f) that Holders will be entitled to withdraw their election if the Paying
Agent receives, not later than the close of business on the second Business Day
preceding the Change of Control Payment Date, a telegram, telex, facsimile
transmission or letter setting forth the name of the Holder, the principal
amount of Notes delivered for purchase, and a statement that such Holder is
withdrawing its election to have the Notes purchased;

     (g) that Holders whose Notes are being purchased only in part will be
issued new Notes equal in principal amount to the unpurchased portion of the
Notes surrendered, which unpurchased portion must be equal to $1,000 in
principal amount or an integral multiple thereof; and

     (h) that Holders electing to have a Note purchased pursuant to a Change of
Control Offer may elect to have Notes purchased in integral multiples of $1,000
only.

     On the Change of Control Payment Date, the Company shall, to the extent
lawful,

          (i) accept for payment all Notes or portions of the Notes properly
     tendered pursuant to the Change of Control Offer;

          (ii) deposit with the Paying Agent an amount equal to the Change of
     Control Payment in respect of all Notes or portions of the Notes so
     tendered; and

          (iii) deliver or cause to be delivered to the Trustee the Notes so
     accepted together with an Officers' Certificate stating the aggregate
     principal amount of Notes or portions thereof being purchased by the
     Company.

     The Paying Agent shall promptly mail to each Holder of Notes properly
tendered payment in an amount equal to the Change of Control Payment with
respect to the purchased Notes, and the Trustee shall promptly authenticate and
mail (or cause to be transferred by book

                                      -12-
<PAGE>

entry) to each Holder a new Note equal in principal amount to any unpurchased
portion of the Notes surrendered by such Holder, if any; PROVIDED, HOWEVER, that
each such new Note shall be in a principal amount of $1,000 or an integral
multiple thereof. The Company shall publicly announce the results of the Change
of Control Offer on or as soon as practicable after the Change of Control
Payment Date.

     The Change of Control provisions described above shall be applicable
whether or not any other provisions of this Indenture are applicable.

     The Company shall comply with the requirements of Section 14(e) of the
Exchange Act and any other securities laws or regulations to the extent those
laws and regulations are applicable to any Change of Control Offer. If the
provisions of any of the applicable securities laws or securities regulations
conflict with the provisions of this Section 4.1, the Company shall comply with
the applicable securities laws and regulations and shall not be deemed to have
breached its obligations under this Section 4.1 by virtue of the compliance.

     Notwithstanding the foregoing provisions of this Section 4.1, the Company
shall not be required to make or give notice of a Change of Control Offer and,
if made or given, shall not be required to repurchase Notes on the related
Change of Control Payment Date if, prior to the date on which such notice or
Change of Control Offer is required to be given or made or such Change of
Control Payment Date, as applicable

          (i) the Company shall have irrevocably exercised its option to redeem
     the Notes in whole pursuant to Section 2.1(d) of this Supplemental
     Indenture; PROVIDED that if the Company shall default in its obligation to
     redeem the Notes pursuant to such redemption on the applicable Redemption
     Date, the Company shall become obligated to commence a Change of Control
     Offer in accordance with this Article 4 on such Redemption Date; or

          (ii) giving effect to the related Change of Control, the Moody's and
     Standard & Poor's shall have confirmed that the Notes are rated "Ba3" (or
     its equivalent) or higher and "BB-" or higher, respectively.

     The Company shall not be required to make a Change of Control Offer upon a
Change of Control if a third party makes the Change of Control Offer in the
manner, at the times and otherwise in compliance with the requirements set forth
in this Indenture applicable to a Change of Control Offer made by the Company
and purchases all Notes properly tendered and not withdrawn under such Change of
Control Offer.

     The provisions of the Indenture relating to the Company's obligation to
make an offer to repurchase the Notes as a result of a Change of Control
(including this Article 4 and clause (a) of Section 5.1) may be waived or
modified with the consent of the Holders of at least a majority in principal
amount of the Notes then outstanding.

     SECTION 4.2. The provisions of Section 4.1 shall terminate and cease to
have further force or effect on or after the first date, if any, on which the
Notes shall have been rated "Baa3" (or its

                                      -13-
<PAGE>

equivalent) or higher by Moody's and "BBB-" (or its equivalent) or higher by
Standard & Poor's.

                                    ARTICLE 5

                          ADDITIONAL EVENTS OF DEFAULT

     SECTION 5.1 For purposes of this Supplemental Indenture and the Notes, in
addition to the Events of Default set forth in Section 501 of the Indenture, it
shall also constitute an "Event of Default" if (a) the Company shall have failed
to consummate a Change of Control Offer in accordance with the provisions of
Article 4 of this Supplemental Indenture, or (b) one or more final judgments or
orders (not covered by insurance, treating any deductibles, self-insurance or
retention as not so covered) for the payment of money in excess of $10,000,000
in the aggregate for all such judgments or orders against the Company or any
Subsidiary and such judgments or orders shall not be paid or discharged, and
there shall be a period of 60 consecutive days after the final judgment or order
that causes such aggregate amount to exceed $10,000,000 million during which a
stay of enforcement of such final judgment(s) or order(s) are not in effect.

     SECTION 5.2 Notwithstanding any provisions to the contrary in the Indenture
including, without limitation, Section 501(a) thereof, the failure to pay the
principal of or any premium on the Notes at its Maturity shall constitute an
"Event of Default".

     SECTION 5.3 Notwithstanding any provisions to the contrary in the Indenture
including, without limitation, Section 501(e) thereof, the default under any
bonds, debentures, notes or other evidences of indebtedness of the Company, or
under any mortgage, indenture or other instrument of the Company (including a
default with respect to Securities of any series other than the Notes) under
which there may be issued or by which there may be secured any indebtedness of
the Company (or by one or more Subsidiaries, the repayment of which the Company
has guaranteed or for which the Company is directly responsible or liable as
obligor or guarantor), whether such indebtedness now exists or shall hereafter
be created, which default(s) shall constitute a failure to pay an aggregate
principal amount exceeding $10,000,000 of such indebtedness when due and payable
after the expiration of any applicable grace period with respect thereto and
shall have resulted in such indebtedness in an aggregate principal amount
exceeding $10,000,000 becoming or being declared due and payable prior to the
date on which it would otherwise have become due and payable, without such
indebtedness having been discharged, or such acceleration having been rescinded
or annulled, within a period of 10 days after there shall have been given, by
registered or certified mail, to the Company by the Trustee or to the Company
and the Trustee by the Holders of at least a majority in principal amount of the
Outstanding Notes a written notice specifying such default and requiring the
Company to cause such indebtedness to be discharged or cause such acceleration
to be rescinded or annulled and stating that such notice is a "NOTICE OF
DEFAULT" hereunder, shall constitute an Event of Default.

     SECTION 5.4. Notwithstanding any provisions to the contrary in the
Indenture, upon the acceleration of the Notes in accordance with Section 502 of
the Indenture, the amount

                                      -14-
<PAGE>

immediately due and payable in respect of the Notes shall equal the Outstanding
principal amount thereof, plus accrued and unpaid interest, plus the Make Whole
Amount.

                                    ARTICLE 6

                                  EFFECTIVENESS

     SECTION 6.1 This Supplemental Indenture shall be effective for all purposes
as of the date and time this Supplemental Indenture has been executed and
delivered by the Company and the Trustee in accordance with Article Nine of the
Indenture. As supplemented hereby, the Indenture is hereby confirmed as being in
full force and effect.

                                    ARTICLE 7

                                NOTICE TO TRUSTEE

     SECTION 7.1 Notwithstanding anything to the contrary in the Indenture
including, without limitation, Section 1102 thereof, in connection with the
redemption at the election of the Company of less than all the Notes, the
Company shall notify the Trustee of the establishment of a Redemption Date and
the principal amount of Notes to be redeemed at least 45 days prior to such
Redemption Date unless a shorter period shall be satisfactory to the Trustee.

                                    ARTICLE 8

                                  MISCELLANEOUS

     SECTION 8.1 In the event any provision of this Supplemental Indenture shall
be held invalid or unenforceable by any court of competent jurisdiction, such
holding shall not invalidate or render unenforceable any other provision hereof
or any provision of the Indenture.

     SECTION 8.2 To the extent that any terms of this Supplemental Indenture or
the Notes are inconsistent with the terms of the Indenture, the terms of this
Supplemental Indenture or the Notes shall govern and supersede such inconsistent
terms.

     SECTION 8.3 This Supplemental Indenture shall be governed by and construed
in accordance with the laws of the State of New York.

     SECTION 8.4 This Supplemental Indenture may be executed in several
counterparts, each of which shall be an original and all of which shall
constitute but one and the same instrument.

                                      -15-
<PAGE>

     IN WITNESS WHEREOF, the Company and the Trustee have caused this
Supplemental Indenture to be executed as an instrument under seal in their
respective corporate names as of the date first above written.

                                            SENIOR HOUSING PROPERTIES TRUST

                                            By: /s/ David J. Hegarty
                                                ----------------------------
                                                David J. Hegarty
                                                President

                                            STATE STREET BANK AND TRUST
                                            COMPANY, as Trustee

                                            By: /s/ Alison D.B. Nadeau
                                                ----------------------------
                                                Alison D.B. Nadeau
                                                Vice President

                                      -16-
<PAGE>

                                                                       EXHIBIT A

                                  FORM OF NOTE

                           [Form of Face of Security]

                         SENIOR HOUSING PROPERTIES TRUST

                          8-5/8% Senior Notes due 2012

No. ____                                                           $ ___________

     Senior Housing Properties Trust, a real estate investment trust duly
organized and existing under the laws of Maryland (herein called the "COMPANY",
which term includes any successor Person under the Indenture hereinafter
referred to), for value received, hereby promises to pay to____________________,
or registered assigns, the principal sum of ___________________ Dollars
($_____________) on January 15, 2012, and to pay interest thereon from December
20, 2001 or from the most recent Interest Payment Date to which interest has
been paid or duly provided for, semi-annually on January 15 and July 15 in each
year, commencing July 15, 2002 at the rate of 8-5/8% per annum, until the
principal hereof is paid or made available for payment. The interest so payable,
and punctually paid or duly provided for, on any Interest Payment Date will, as
provided in such Indenture, be paid to the Person in whose name this Security
(or one or more Predecessor Securities) is registered at the close of business
on the Regular Record Date for such interest, which shall be the January 1 or
July 1 (whether or not a Business Day), as the case may be, next preceding such
Interest Payment Date. Any such interest not so punctually paid or duly provided
for will forthwith cease to be payable to the Holder on such Regular Record Date
and may either be paid to the Person in whose name this Security (or one or more
Predecessor Securities) is registered at the close of business on a Special
Record Date for the payment of such Defaulted Interest to be fixed by the
Trustee, notice whereof shall be given to Holders of Securities of this series
not less than 10 days prior to such Special Record Date, or be paid at any time
in any other lawful manner not inconsistent with the requirements of any
securities exchange on which the Securities of this series may be listed, and
upon such notice as may be required by such exchange, all as more fully provided
in said Indenture.

     Payment of the principal of (and premium, if any) and any such interest on
this Security will be made at the office or agency of the Company maintained for
that purpose in such coin or currency of the United States of America as at the
time of payment is legal tender for payment of public and private debts;
PROVIDED, HOWEVER, that at the option of the Company payment of interest may be
made by check mailed to the address of the Person entitled thereto as such
address shall appear in the Security Register.

     Reference is hereby made to the further provisions of this Security set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

     Unless the certificate of authentication hereon has been executed by the
Trustee referred to on the reverse hereof by manual signature, this Security
shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

     THE ARTICLES OF AMENDMENT AND RESTATEMENT ESTABLISHING SENIOR HOUSING
PROPERTIES TRUST DATED SEPTEMBER 20, 1999, A COPY OF WHICH, TOGETHER WITH ALL
AMENDMENTS THERETO (THE "DECLARATION"), IS DULY FILED IN THE OFFICE OF THE
DEPARTMENT OF ASSESSMENTS AND TAXATION OF THE STATE OF MARYLAND, PROVIDES THAT
THE NAME "SENIOR HOUSING PROPERTIES TRUST" REFERS TO THE TRUSTEES UNDER THE
DECLARATION COLLECTIVELY AS TRUSTEES, BUT NOT INDIVIDUALLY OR PERSONALLY, AND
THAT NO TRUSTEE, OFFICER, SHAREHOLDER, EMPLOYEE OR AGENT OF THE COMPANY SHALL BE
HELD TO ANY PERSONAL LIABILITY, JOINTLY OR SEVERALLY, FOR ANY OBLIGATION OF, OR
CLAIM AGAINST, THE COMPANY. ALL PERSONS DEALING WITH THE COMPANY, IN ANY WAY,
SHALL LOOK ONLY TO THE

                                       A-1
<PAGE>

ASSETS OF THE COMPANY FOR THE PAYMENT OF ANY SUM OR THE PERFORMANCE OF ANY
OBLIGATION.

     IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.

Dated:                                     SENIOR HOUSING PROPERTIES TRUST

                                           By___________________________
                                             Title:

                          CERTIFICATE OF AUTHENTICATION

Dated:

     This is one of the Securities of the series designated therein referred to
in the within-mentioned Indenture.

                                           [STATE STREET BANK AND TRUST
                                            COMPANY], AS TRUSTEE

                                           By___________________________
                                              AUTHORIZED OFFICER

                                      A-2

<PAGE>

                          [Form of Reverse of Security]

     1. GENERAL. This Security is one of a duly authorized issue of securities
of the Company (herein called the "SECURITIES"), issued and to be issued in one
or more series under an Indenture, dated as of December 20, 2001 (as amended,
supplemented or otherwise modified from time to time, the "BASE INDENTURE"), as
supplemented by a Supplemental Indenture No. 1, dated as of December 20, 2001
(as amended, supplemented or otherwise modified from time to time, the
"SUPPLEMENTAL INDENTURE" and the Base Indenture, as supplemented by such
Supplemental Indenture, the "INDENTURE"), each between the Company and State
Street Bank and Trust Company, as Trustee (herein called the "TRUSTEE", which
term includes any successor trustee under the Indenture), and reference is
hereby made to the Indenture for a statement of the respective rights,
limitations of rights, duties and immunities thereunder of the Company, the
Trustee, and the Holders of the Securities and of the terms upon which the
Securities are, and are to be, authenticated and delivered. This Security is one
of the series designated on the face hereof.

     2. OPTIONAL REDEMPTION. The Securities of this series are subject to
redemption upon not less than 30 nor more than 60 days' notice by mail, at any
time or from time to time, as a whole or in part, at the election of the
Company, at a redemption price equal to the sum of (i) the principal amount of
the Notes being redeemed, (ii) accrued and unpaid interest to but excluding the
applicable Redemption Date and (iii) the Make-Whole Amount, if any.

     In the event of redemption of this Security in part only, a new Security or
Securities of this series and of like tenor for the unredeemed portion hereof
will be issued in the name of the Holder hereof upon the cancellation hereof.

     3. DEFEASANCE. The Indenture contains provisions for defeasance at any time
of the entire indebtedness of this Security upon compliance with certain
conditions set forth in the Indenture.

     4. DEFAULTS AND REMEDIES. If an Event of Default with respect to Securities
of this series shall occur and be continuing, the principal of the Securities of
this series may be declared due and payable in the manner and with the effect
provided in the Indenture.

     5. ACTIONS OF HOLDERS. The Indenture permits, with certain exceptions as
therein provided, the amendment thereof and the modification of the rights and
obligations of the Company and the rights of the Holders of the Securities of
each series to be affected under the Indenture at any time by the Company and
the Trustee with the consent of the Holders of a majority in principal amount of
the Securities at the time Outstanding of each series to be affected. The
Indenture also contains provisions permitting the Holders of specified
percentages in principal amount of the Securities of each series at the time
Outstanding, on behalf of the Holders of all Securities of such series, to waive
compliance by the Company with certain provisions of the Indenture and certain
past defaults under the Indenture and their consequences. Any such consent or
waiver by the Holder of this Security shall be conclusive and binding upon such
Holder and upon all future Holders of this Security and of any Security issued
upon the registration of transfer hereof or in exchange therefor or in lieu
hereof, whether or not notation of such consent or waiver is made upon this
Security.

     As provided in and subject to the provisions of the Indenture, the Holder
of this Security shall not have the right to institute any proceeding with
respect to the Indenture or for the appointment of a receiver or trustee or for
any other remedy thereunder, unless such Holder shall have previously given the
Trustee written notice of a continuing Event of Default with respect to the
Securities of this series, the Holders of not less than a majority in principal
amount of the Securities of this series at the time Outstanding shall have made
written request to the Trustee to institute proceedings in respect of such Event
of Default as Trustee and offered the Trustee reasonable indemnity, and the
Trustee shall not have received from the Holders of a majority in principal
amount of Securities of this series at the time Outstanding a direction
inconsistent with such request, and shall have failed to institute any such
proceeding, for 60 days after receipt of such notice, request and offer of
indemnity. The foregoing shall not apply to any suit instituted by the Holder of
this Security for the enforcement of any payment of principal hereof or any
premium or interest hereon on or after the respective due dates expressed
herein.

                                      A-3

<PAGE>

     6. PAYMENTS NOT IMPAIRED. No reference herein to the Indenture and no
provision of this Security or of the Indenture shall alter or impair the
obligation of the Company, which is absolute and unconditional, to pay the
principal of and any premium and interest on this Security at the times, place
and rate, and in the coin or currency, herein prescribed.

     7. DENOMINATIONS, TRANSFER, EXCHANGE. As provided in the Indenture and
subject to certain limitations therein set forth, the transfer of this Security
is registrable in the Security Register, upon surrender of this Security for
registration of transfer at the office or agency of the Company in any place
where the principal of and any premium and interest on this Security are
payable, duly endorsed by, or accompanied by a written instrument of transfer in
form satisfactory to the Company and the Security Registrar duly executed by,
the Holder hereof or his attorney duly authorized in writing, and thereupon one
or more new Securities of this series and of like tenor, of authorized
denominations and for the same aggregate principal amount, will be issued to the
designated transferee or transferees.

     The Securities of this series are issuable only in registered form without
coupons in denominations of $1,000 and any integral multiple thereof. As
provided in the Indenture and subject to certain limitations therein set forth,
Securities of this series are exchangeable for a like aggregate principal amount
of Securities of this series and of like tenor of a different authorized
denomination, as requested by the Holder surrendering the same.

     No service charge shall be made for any such registration of transfer or
exchange, but the Company may require payment of a sum sufficient to cover any
tax or other governmental charge payable in connection therewith.

     8. PERSONS DEEMED OWNERS. Prior to due presentment of this Security for
registration of transfer, the Company, the Trustee and any agent of the Company
or the Trustee may treat the Person in whose name this Security is registered as
the owner hereof for all purposes, whether or not this Security be overdue, and
neither the Company, the Trustee nor any such agent shall be affected by notice
to the contrary.

     9. DEFINED TERMS. All terms used in this Security which are defined in the
Indenture shall have the meanings assigned to them in the Indenture.

                                      A-4

<PAGE>

                                [ASSIGNMENT FORM]

                                  ABBREVIATIONS

     The following abbreviations, when used in the inscription on the face of
this instrument, shall be construed as though they were written out in full
according to applicable laws or regulations:

<TABLE>
<S>                                                        <C>
TEN COM --  as tenants in common                             UNIF GIFT MIN ACT -- _____ Custodian______
TEN ENT --  as tenants by the entireties                                          (Cust)         (Minor)
JT TEN  --  as joint tenants with right of survivorship                           Under Uniform Gifts to Minors
            and not as tenants in common                                          Act_______
                                                                                     (State)
</TABLE>

    Additional abbreviations may also be used though not in the above list.

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

FOR VALUE RECEIVED, the undersigned registered holder hereby sell(s), assign(s)
and transfer(s) unto

PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE

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

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

--------------------------------------------------------------------------------
             PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS OF ASSIGNEE

--------------------------------------------------------------------------------
the within security and all rights thereunder, hereby irrevocably constituting
and appointing

----------------------------------------------------------------------- Attorney
to transfer said security on the books of the Company with full power of
substitution in the premises.

Dated:                                 Signed:
      --------------------------               ------------------------------

                                       Notice: The signature to this assignment
                                       must correspond with the name as it
                                       appears upon the face of the within
                                       security in every particular, without
                                       alteration or enlargement or any change
                                       whatever.

                                       Signature Guarantee*:___________________

                                       * Participant in a recognized Signature
                                       Guarantee Medallion Program (or other
                                       signature guarantor acceptable to the
                                       Trustee).

                                      A-5

<PAGE>

                                   [FORM OF OPTION OF HOLDER TO ELECT PURCHASE]

                       OPTION OF HOLDER TO ELECT PURCHASE

If you want to elect to have this Note purchased by the Company pursuant to
Section 4.2 of the Supplemental Indenture referred to in this Note pursuant to
the Company's Change of Control Offer, check this box: [__]

If you want to elect to have only part of this Note purchased by the Company
pursuant to Section 4.2 of the Supplemental Indenture referred to in this Note
pursuant to the Company's Change of Control Offer, state the amount you elect to
have purchased (must be an integral multiple of $1,000): $__________________

PLEASE INSERT YOUR SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER:

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

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

Dated:                                  Signed:
      --------------------------                --------------------------------

                                        Notice: The signature to this election
                                        must correspond with the name as it
                                        appears upon the face of the within
                                        security in every particular, without
                                        alteration or enlargement or any change
                                        whatever.

                                        Signature Guarantee*:___________________

                                        * Participant in a recognized Signature
                                        Guarantee Medallion Program (or other
                                        signature guarantor acceptable to the
                                        Company).

                                      A-6<PAGE>

                                   EXHIBIT 4.2

                          SUPPLEMENTAL INDENTURE NO. 2

                                 BY AND BETWEEN

                         SENIOR HOUSING PROPERTIES TRUST

                                       AND

                       STATE STREET BANK AND TRUST COMPANY

                             AS OF DECEMBER 28, 2001

           SUPPLEMENTAL TO THE INDENTURE DATED AS OF DECEMBER 20, 2001

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

                         SENIOR HOUSING PROPERTIES TRUST

                     ADDITIONAL 8-5/8% SENIOR NOTES DUE 2012

<PAGE>

     This SUPPLEMENTAL INDENTURE NO. 2 (this "SUPPLEMENTAL INDENTURE") made and
entered into as of December 28, 2001 between SENIOR HOUSING PROPERTIES TRUST, a
Maryland real estate investment trust (the "Company"), and STATE STREET BANK AND
TRUST COMPANY, a Massachusetts trust company, as Trustee (the "TRUSTEE"),

                                WITNESSETH THAT:

     WHEREAS, the Company and the Trustee have executed and delivered an
Indenture, dated as of December 20, 2001 (as amended, supplemented or otherwise
modified from time to time, the "BASE INDENTURE") to provide for the issuance of
the Company's senior debt securities (the "SECURITIES") to be issued from time
to time in one or more series;

     WHEREAS, the Company and the Trustee have also executed and delivered a
Supplemental Indenture No. 1, dated as of December 20, 2001 (as amended,
supplemented or otherwise modified from time to time, "SUPPLEMENTAL INDENTURE
NO. 1") supplementing the Base Indenture (as so supplemented, the "INDENTURE")
to provide for the establishment of a series of its Securities known as its
8-5/8% Senior Notes due 2012 (such series, the "NOTES DUE 2012") issued in an
initial aggregate principal amount of $200,000,000; and

     WHEREAS, the Company desires to reopen the such series of Securities
pursuant to Section 301 of the Base Indenture and Section 2.1(a) of Supplemental
Indenture No. 1 to authorize the issuance of an additional $45,000,000 in
aggregate principal amount of Notes due 2012 pursuant to the terms and
conditions established thereunder;

     NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH:

     SECTION 1. ADDITIONAL NOTES DUE 2012. The Indenture, including Section
2.1(a) of Supplemental Indenture No. 1, is hereby supplemented to provide that
the Notes due 2012 will be limited to an aggregate principal amount of
$245,000,000, subject to the continued right of the Company to reopen such
series for issuances of additional Securities of such series and except (i) as
provided in Section 2.1 of Supplemental Indenture No. 1 and (ii) for Securities
authenticated and delivered upon registration of transfer of, or in exchange
for, or in lieu of, other Notes due 2012 pursuant to Section 304, 305, 306, 906
or 1107 of the Base Indenture and except for any Notes due 2012 which, pursuant
to Section 303 of the Base Indenture, are deemed never to have been
authenticated and delivered thereunder.

     SECTION 2. EFFECTIVENESS. This Supplemental Indenture shall be effective
for all purposes as of the date and time this Supplemental Indenture has been
executed and delivered by the Company and the Trustee in accordance with Article
Nine of the Base Indenture. As supplemented hereby, the Indenture is hereby
confirmed as being in full force and effect.

     SECTION 3. MISCELLANEOUS. (a) In the event any provision of this
Supplemental Indenture shall be held invalid or unenforceable by any court of
competent jurisdiction, such holding shall not invalidate or render
unenforceable any other provision hereof or any provision of the Indenture.

<PAGE>

          (b) To the extent that any terms of this Supplemental Indenture are
inconsistent with the terms of the Indenture, the terms of this Supplemental
Indenture shall govern and supersede such inconsistent terms.

          (c) This Supplemental Indenture shall be governed by and construed in
accordance with the laws of the State of New York.

          (d) This Supplemental Indenture may be executed in several
counterparts, each of which shall be an original and all of which shall
constitute but one and the same instrument.

                            [Signature Page Follows]

                                      -2-

<PAGE>

     IN WITNESS WHEREOF, the Company and the Trustee have caused this
Supplemental Indenture to be executed as an instrument under seal as of the date
first above written.

                                             SENIOR HOUSING PROPERTIES TRUST

                                             By: /s/ David J. Hegarty
                                                 ----------------------------
                                                 David J. Hegarty
                                                 President

                                             STATE STREET BANK AND TRUST
                                             COMPANY, as Trustee

                                             By: /s/ Alison D.B. Nadeau
                                                 ----------------------------
                                                 Alison D.B. Nadeau
                                                 Vice President

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