<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2004-01-13</periodOfReport>
    <issuer>
        <issuerCik>0000740260</issuerCik>
        <issuerName>VENTAS INC</issuerName>
        <issuerTradingSymbol>VTR</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001215185</rptOwnerCik>
            <rptOwnerName>RINEY T RICHARD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10350 ORMSBY PARK PLACE, SUITE 300</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LOUISVILLE,</rptOwnerCity>
            <rptOwnerState>KY</rptOwnerState>
            <rptOwnerZipCode>40223</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Exec.V.P., General Counsel</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2004-01-13</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>10086</value><footnoteId id="F1"/></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>274239</value><footnoteId id="F2"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><derivativeTable><derivativeTransaction><securityTitle><value>Stock Option (Right to Buy)</value></securityTitle><conversionOrExercisePrice><value>23.00</value></conversionOrExercisePrice><transactionDate><value>2004-01-13</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>48033</value><footnoteId id="F3"/></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F4"/></exerciseDate><expirationDate><value>2014-01-13</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>48033</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>308179</value><footnoteId id="F5"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">These shares represent restricted shares granted under the 2000 Incentive Compensation Plan.  The shares vest in cumulative 1/3 annual installments commencing 01/13/04.</footnote><footnote id="F2">Reporting Person also owns 1,300 shares indirectly by IRA.</footnote><footnote id="F3">Options granted under the 2000 Incentive Compensation Plan.</footnote><footnote id="F4">The options are exercisable in cumulative 1/3 annual installments beginning on 1/13/04.</footnote><footnote id="F5">Represents total number of unexercised stock options held by Mr. Riney as of 1/13/04.</footnote></footnotes><remarks/><ownerSignature><signatureName>T. Richard Riney</signatureName><signatureDate>2004-01-15</signatureDate></ownerSignature></ownershipDocument>
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X0201
4
2004-01-13
0000740260
VENTAS INC
VTR
0001215185
RINEY T RICHARD
10350 ORMSBY PARK PLACE, SUITE 300
LOUISVILLE,
KY
40223
0
1
0
0
Exec.V.P., General Counsel
Common Stock
2004-01-13
4
A
0
10086
0
A
274239
D
Stock Option (Right to Buy)
23.00
2004-01-13
4
A
0
48033
0
A
2014-01-13
Common Stock
48033
308179
D
These shares represent restricted shares granted under the 2000 Incentive Compensation Plan.  The shares vest in cumulative 1/3 annual installments commencing 01/13/04.
Reporting Person also owns 1,300 shares indirectly by IRA.
Options granted under the 2000 Incentive Compensation Plan.
The options are exercisable in cumulative 1/3 annual installments beginning on 1/13/04.
Represents total number of unexercised stock options held by Mr. Riney as of 1/13/04.
T. Richard Riney
2004-01-15