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

    <documentType>4</documentType><periodOfReport>2004-01-05</periodOfReport>
    <issuer>
        <issuerCik>0000740260</issuerCik>
        <issuerName>VENTAS INC</issuerName>
        <issuerTradingSymbol>VTR</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000939563</rptOwnerCik>
            <rptOwnerName>GEARY RONALD G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10140 LINN STATION ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LOUISVILLE</rptOwnerCity>
            <rptOwnerState>KY</rptOwnerState>
            <rptOwnerZipCode>40223</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Stock Option (Right to Buy)</value></securityTitle><conversionOrExercisePrice><value>22.15</value></conversionOrExercisePrice><transactionDate><value>2004-01-05</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>5000</value><footnoteId id="F1"/></transactionShares><transactionPricePerShare><value>22.15</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2004-01-05</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2014-01-05</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>5000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>40000</value><footnoteId id="F3"/><footnoteId id="F4"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Options granted pursuant to the Ventas, Inc. 2000 Stock Option Plan for Directors.</footnote><footnote id="F2">The options are exercisable in cumulative 50% annual installments beginning on 1/5/04.</footnote><footnote id="F3">Represents the total number of unexercised stock options held by Mr. Geary as of January 5, 2004.</footnote><footnote id="F4">As of January 5, 2004, Reporting Person also owns 2,425 shares of Issuer's common stock.</footnote></footnotes><remarks/><ownerSignature><signatureName>Ronald G. Geary By: T. Richard Riney, Attorney-In-Fact</signatureName><signatureDate>2004-01-07</signatureDate></ownerSignature></ownershipDocument>
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X0201
4
2004-01-05
0000740260
VENTAS INC
VTR
0000939563
GEARY RONALD G
10140 LINN STATION ROAD
LOUISVILLE
KY
40223
1
0
0
0
Stock Option (Right to Buy)
22.15
2004-01-05
4
A
0
5000
22.15
A
2004-01-05
2014-01-05
Common Stock
5000
40000
D
Options granted pursuant to the Ventas, Inc. 2000 Stock Option Plan for Directors.
The options are exercisable in cumulative 50% annual installments beginning on 1/5/04.
Represents the total number of unexercised stock options held by Mr. Geary as of January 5, 2004.
As of January 5, 2004, Reporting Person also owns 2,425 shares of Issuer's common stock.
Ronald G. Geary By: T. Richard Riney, Attorney-In-Fact
2004-01-07