<?xml version="1.0"?><ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2003-08-12</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0001040593</issuerCik><issuerName>CARRIZO OIL &amp; GAS INC</issuerName>        <issuerTradingSymbol>CRZO</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001257331</rptOwnerCik><rptOwnerName>BOLING PAUL F</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1></rptOwnerStreet1><rptOwnerStreet2>SUITE 800</rptOwnerStreet2><rptOwnerCity>HOUSTON</rptOwnerCity><rptOwnerState>TX</rptOwnerState><rptOwnerZipCode>77079</rptOwnerZipCode><rptOwnerStateDescription></rptOwnerStateDescription></reportingOwnerAddress><reportingOwnerRelationship><isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Vice President and CFO</officerTitle></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Nonqualified stock option (right to buy)</value></securityTitle><conversionOrExercisePrice><value>5.725</value></conversionOrExercisePrice><transactionDate><value>2003-08-12</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>20000</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2004-08-12</value><footnoteId id="F1" /></exerciseDate><expirationDate><value>2013-08-12</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>20000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>20000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">The options are exercisable in cumulative annual increments of 1/3 of the total number of shares of Common Stock subject thereto, beginning August 12, 2004, the first anniversary of the date of the grant</footnote></footnotes><ownerSignature><signatureName> /s/ Paul F. Boling</signatureName><signatureDate>2003-08-14</signatureDate></ownerSignature></ownershipDocument>

