<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2007-08-07</periodOfReport>

    <dateOfOriginalSubmission>2007-08-09</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001287865</issuerCik>
        <issuerName>MEDICAL PROPERTIES TRUST INC</issuerName>
        <issuerTradingSymbol>MPW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001067414</rptOwnerCik>
            <rptOwnerName>HAMNER R STEVEN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1000 URBAN CENTER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 501</rptOwnerStreet2>
            <rptOwnerCity>BIRMINGHAM</rptOwnerCity>
            <rptOwnerState>AL</rptOwnerState>
            <rptOwnerZipCode>35242</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP and CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $.001</value>
            </securityTitle>
            <transactionDate>
                <value>2007-08-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>110000</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>388351</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>LTIP Units</value>
                <footnoteId id="F3"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-08-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>75000</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock,par value $.001</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>75000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>75000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">LTIP Units vest ratably on December 31 of each year over a seven year period beginning December 31, 2007.</footnote>
        <footnote id="F2">Represents shares of restricted stock awarded as core performance awards (CPRE). CPRE vest annually and ratably over a 7 year period (beginning 3/1/07 through 12/31/13) contingent on the Company acheiving a simple 9% annual total return to shareholders (pro-rated to 7.5% for the first vesting period from 3/1/07 to 12/31/07). CPRE are subject to forfeiture if less than the full award vests over the 7 year performance measurement period. At the end of each calendar year, the Compensation Committee will determine the Company's pro-rated annual and cumulative total return to shareholders from 3/1/07 through the end of each calendar year. Vesting will occur at the end of each calendar year as follows (pro-rated for 2007): Annual and Cumulative Return per year both less than 9% - 0% vesting; Annual or Cumulative Return equal to or greater than simple 9% - 14.286% vesting; Cumulative Return per year equal to or greather than simple 9% - any unvested portion that failed to vest in prior years.</footnote>
        <footnote id="F3">Represents units of limited partnership interest in MPT Operating Partnership, L.P. (&quot;MPT OP&quot;) of which the Issuer is the general partner, issued as long term incentive compensation pursuant to the Issuer's Second Amended and Restated 2004 Equity Incentive Plan. Conditioned upon minimum allocations to the capital accounts of the LTIP Units for federal income tax purposes, each LTIP Unit may be converted, at the election of the holder, into units of profits interest in MPT OP (a &quot;Common Unit&quot;).  Each Common Unit acquired upon conversion of a LTIP Unit may be presented for redemption, at the election of the holder, for cash equal to the then fair market value of a share of the Issuer's Common Stock, except that the Issuer may, at its election, acquire each Common Unit so presented for one share of Common Stock.  The rights to convert LTIP Units into Common Units and redeem Common Units do not have expiration dates.</footnote>
    </footnotes>

    <remarks>This filing adds the performance based awards made on August 7, 2007.  The time based awards vest on December 31 of each year. The original filing stated this date as March 8 of each year.</remarks>

    <ownerSignature>
        <signatureName>Philip Summerlin, by power of attorney</signatureName>
        <signatureDate>2007-08-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
