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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 BW11xKHSFH3u1G20pURzNZ1LnKkMf/kvtunUjhd+5+T12oaYX55tICHy1ttmvhmN
 f8yiCj7jL0Iy/4qIFV/aDg==

<SEC-DOCUMENT>0001241921-10-000004.txt : 20100301
<SEC-HEADER>0001241921-10-000004.hdr.sgml : 20100301
<ACCEPTANCE-DATETIME>20100301172511
ACCESSION NUMBER:		0001241921-10-000004
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100225
FILED AS OF DATE:		20100301
DATE AS OF CHANGE:		20100301

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Krueger John D
		CENTRAL INDEX KEY:			0001446146

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08430
		FILM NUMBER:		10646176

	MAIL ADDRESS:	
		STREET 1:		777 N. ELDRIDGE PARKWAY
		STREET 2:		12TH FLOOR
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77079

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MCDERMOTT INTERNATIONAL INC
		CENTRAL INDEX KEY:			0000708819
		STANDARD INDUSTRIAL CLASSIFICATION:	FABRICATED PLATE WORK (BOILER SHOPS) [3443]
		IRS NUMBER:				720593134
		STATE OF INCORPORATION:			R1
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		777 N. ELDRIDGE PARKWAY
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77079
		BUSINESS PHONE:		281-870-5000

	MAIL ADDRESS:	
		STREET 1:		777 N. ELDRIDGE PARKWAY
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77079
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-02-25</periodOfReport>

    <issuer>
        <issuerCik>0000708819</issuerCik>
        <issuerName>MCDERMOTT INTERNATIONAL INC</issuerName>
        <issuerTradingSymbol>MDR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001446146</rptOwnerCik>
            <rptOwnerName>Krueger John D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MCDERMOTT INTERNATIONAL, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>777 N. ELDRIDGE PARKWAY</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>VP- Corp. Devlp. &amp; Strat. Plan</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Performance Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-02-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>11730</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2010-05-10</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>11730</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11730</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each performance share represents a contingent right to receive one share of MDR common stock.</footnote>
        <footnote id="F2">Each performance share represents a contingent right to receive one share of MDR common stock.  The performance shares vest on May 10, 2010, provided the reporting person is still an employee of the Company on that date, subject to limited exceptions.</footnote>
        <footnote id="F3">On May 10, 2007, the reporting person was granted a target number of performance shares, with the payout from 0 to 150% of target based on the Company's total consolidated operating income over a three-year period.  The payout was determined on February 25, 2010, resulting in the reported number of performance shares received.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Liane K. Hinrichs, by power of attorney</signatureName>
        <signatureDate>2010-03-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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