-----BEGIN PRIVACY-ENHANCED MESSAGE-----
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,
 VhlCHr8qEf2gjXqxCj5FCeTv5RAE3KNj4Bir4pkgg0WrERZdgx9LF7gtf9tKewI+
 s859r5aNthhBQFGLgwmQ+Q==

<SEC-DOCUMENT>0000075362-09-000124.txt : 20091207
<SEC-HEADER>0000075362-09-000124.hdr.sgml : 20091207
<ACCEPTANCE-DATETIME>20091207205018
ACCESSION NUMBER:		0000075362-09-000124
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20091207
FILED AS OF DATE:		20091207
DATE AS OF CHANGE:		20091207

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HACHIGIAN KIRK S
		CENTRAL INDEX KEY:			0001210484

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-14817
		FILM NUMBER:		091227392

	MAIL ADDRESS:	
		STREET 1:		C/O COOPER INDUSTRIES INC
		STREET 2:		600 TRAVIS STE 5800
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PACCAR INC
		CENTRAL INDEX KEY:			0000075362
		STANDARD INDUSTRIAL CLASSIFICATION:	MOTOR VEHICLES & PASSENGER CAR BODIES [3711]
		IRS NUMBER:				910351110
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		PACCAR BUILDING
		STREET 2:		777 106TH AVENUE NE
		CITY:			BELLEVUE
		STATE:			WA
		ZIP:			98004
		BUSINESS PHONE:		425 468 7383

	MAIL ADDRESS:	
		STREET 1:		PACCAR BUILDING
		STREET 2:		777 106TH AVENUE NE
		CITY:			BELLEVUE
		STATE:			WA
		ZIP:			98004

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	PACIFIC CAR & FOUNDRY CO
		DATE OF NAME CHANGE:	19720707
</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>2009-12-07</periodOfReport>

    <issuer>
        <issuerCik>0000075362</issuerCik>
        <issuerName>PACCAR INC</issuerName>
        <issuerTradingSymbol>PCAR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001210484</rptOwnerCik>
            <rptOwnerName>HACHIGIAN KIRK S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>777 106TH AVENUE N.E.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BELLEVUE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98004</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>STOCK UNITS (RSDCP)</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2009-12-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>9.3</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>35.97</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>9.3</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3724.49</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Restricted stock units held in deferred phantom stock account under PACCAR Restricted Stock and Deferred Compensation Plan for Non-Employee Directors (RSDCP) convertible to PACCAR common stock on a 1-for-1 basis upon satisfaction of all applicable vesting conditions.</footnote>
        <footnote id="F2">Dividend on restricted stock units under RSDCP reinvested in additional stock units pursuant to RSDCP.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Kirk S. Hachigian by Janice D'Amato POA</signatureName>
        <signatureDate>2009-12-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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