<?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>0001195500</rptOwnerCik>
            <rptOwnerName>CROCKER DOUGLASS II</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>TWO NORTH RIVERSIDE PLAZA</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</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>240000</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. Crocker as of January 5, 2004.</footnote><footnote id="F4">As of January 5, 2004, Reporting Person also owns 36,518 shares of Issuer's common stock.</footnote></footnotes><remarks/><ownerSignature><signatureName>Douglas Crocker, II 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
0001195500
CROCKER DOUGLASS II
TWO NORTH RIVERSIDE PLAZA
CHICAGO
IL
60606
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
240000
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. Crocker as of January 5, 2004.
As of January 5, 2004, Reporting Person also owns 36,518 shares of Issuer's common stock.
Douglas Crocker, II By: T. Richard Riney, Attorney-In-Fact
2004-01-07