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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 ZhBbx0g5AIB696dL7XWXbA==

<SEC-DOCUMENT>0001140361-04-001222.txt : 20040213
<SEC-HEADER>0001140361-04-001222.hdr.sgml : 20040213
<ACCEPTANCE-DATETIME>20040213135246
ACCESSION NUMBER:		0001140361-04-001222
CONFORMED SUBMISSION TYPE:	5
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031231
FILED AS OF DATE:		20040213

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			DIAMOND OFFSHORE DRILLING INC
		CENTRAL INDEX KEY:			0000949039
		STANDARD INDUSTRIAL CLASSIFICATION:	DRILLING OIL & GAS WELLS [1381]
		IRS NUMBER:				760321760
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		15415 KATY FREEWAY
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77094
		BUSINESS PHONE:		7134925300

	MAIL ADDRESS:	
		STREET 1:		15415 KATY FREEWAY
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77094

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			LOEWS CORP
		CENTRAL INDEX KEY:			0000060086
		STANDARD INDUSTRIAL CLASSIFICATION:	FIRE, MARINE & CASUALTY INSURANCE [6331]
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		5
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13926
		FILM NUMBER:		04597168

	BUSINESS ADDRESS:	
		STREET 1:		667 MADISON AVE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10021-8087
		BUSINESS PHONE:		212-521-2000

	MAIL ADDRESS:	
		STREET 1:		667 MADISON AVE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10021-8087
</SEC-HEADER>
<DOCUMENT>
<TYPE>5
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 5
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>5</documentType>

    <periodOfReport>2003-12-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <form3HoldingsReported>0</form3HoldingsReported>

    <form4TransactionsReported>0</form4TransactionsReported>

    <issuer>
        <issuerCik>0000949039</issuerCik>
        <issuerName>DIAMOND OFFSHORE DRILLING INC</issuerName>
        <issuerTradingSymbol>DO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000060086</rptOwnerCik>
            <rptOwnerName>LOEWS CORP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>667 MADISON AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10021</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2003-12-02</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4620</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>70104620</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This form is being filed to report a change in the form of beneficial ownership of the shares reported herein from indirect to direct as a result of the reporting person's withdrawal of the shares from the Oil Service Holdes Trust, at no cost. The acquisition of the subject shares was previously reported by the reporting person on a Form 4 dated December 4, 2003.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Loews Corporation by Gary W. Garson</signatureName>
        <signatureDate>2004-02-13</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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