<SEC-DOCUMENT>0001104659-11-018010.txt : 20110331
<SEC-HEADER>0001104659-11-018010.hdr.sgml : 20110331
<ACCEPTANCE-DATETIME>20110331173126
ACCESSION NUMBER:		0001104659-11-018010
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20110330
FILED AS OF DATE:		20110331
DATE AS OF CHANGE:		20110331

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SENIOR HOUSING PROPERTIES TRUST
		CENTRAL INDEX KEY:			0001075415
		STANDARD INDUSTRIAL CLASSIFICATION:	REAL ESTATE INVESTMENT TRUSTS [6798]
		IRS NUMBER:				043445278
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		TWO NEWTON PLACE
		STREET 2:		255 WASHINGTON STREET
		CITY:			NEWTON
		STATE:			MA
		ZIP:			02458
		BUSINESS PHONE:		6173323990

	MAIL ADDRESS:	
		STREET 1:		TWO NEWTON PLACE
		STREET 2:		255 WASHINGTON STREET
		CITY:			NEWTON
		STATE:			MA
		ZIP:			02458

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			PORTNOY BARRY M
		CENTRAL INDEX KEY:			0001241559

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15319
		FILM NUMBER:		11727802

	MAIL ADDRESS:	
		STREET 1:		C/O REIT MANAGEMENT & RESEARCH LLC
		STREET 2:		TWO NEWTON PLACE, 255 WASHINGTON STREET
		CITY:			NEWTON
		STATE:			MA
		ZIP:			02458
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-03-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001075415</issuerCik>
        <issuerName>SENIOR HOUSING PROPERTIES TRUST</issuerName>
        <issuerTradingSymbol>NYSE: SNH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001241559</rptOwnerCik>
            <rptOwnerName>PORTNOY BARRY M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEWTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02458</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares of Beneficial Interest</value>
            </securityTitle>
            <transactionDate>
                <value>2011-03-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value>E</value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4916</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>23.02</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>185154.802</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares were issued pursuant to a business management agreement between the issuer and Reit Management &amp; Research LLC (&quot;RMR&quot;) of which Mr. Portnoy is a director and majority beneficial owner. Mr. Portnoy purchased these shares from RMR upon their issuance. Such transfers were exempt from Section 16 of the Securities Exchange Act of 1934, as amended, pursuant to Rule 16a-13 thereunder.</footnote>
        <footnote id="F2">In accordance with the business management agreement referred to above, certain historical share price information was used to determine the number of common shares of beneficial interest paid to RMR. The per share price amount listed above is the closing sale price of the issuer's common shares of beneficial interest on the New York Stock Exchange on March 30, 2011, when the shares were issued and purchased.</footnote>
        <footnote id="F3">Includes 2,935.602 shares acquired under the Senior Housing Properties Trust Dividend Reinvestment Plan since the last Section 16 filing by Mr. Portnoy.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Barry M. Portnoy</signatureName>
        <signatureDate>2011-03-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
