-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 LJmx1dgk4T50CRvEG1hP5q5e/9SuZxmn5AmzyAkR86sfrCkT5tqy1GCkWJzbkGGj
 LdNNRSyQGKkCky3zbFWtbQ==

<SEC-DOCUMENT>0001209191-05-030368.txt : 20050611
<SEC-HEADER>0001209191-05-030368.hdr.sgml : 20050611
<ACCEPTANCE-DATETIME>20050606203126
ACCESSION NUMBER:		0001209191-05-030368
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050602
FILED AS OF DATE:		20050606
DATE AS OF CHANGE:		20050606

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			XENOPORT INC
		CENTRAL INDEX KEY:			0001130591
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				943330837
		STATE OF INCORPORATION:			DE

	BUSINESS ADDRESS:	
		STREET 1:		3410 CENTRAL EXPRESSWAY
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95051
		BUSINESS PHONE:		4086167200

	MAIL ADDRESS:	
		STREET 1:		3410 CENTRAL EXPRESSWAY
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95051

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			NUSSBACHER KENNETH J
		CENTRAL INDEX KEY:			0001216629

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-51329
		FILM NUMBER:		05881645

	MAIL ADDRESS:	
		STREET 1:		C/O SYMYX TECHNOLOGIES, INC.
		STREET 2:		3100 CENTRAL EXPRESSWAY
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95051
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-06-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001130591</issuerCik>
        <issuerName>XENOPORT INC</issuerName>
        <issuerTradingSymbol>XNPT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001216629</rptOwnerCik>
            <rptOwnerName>NUSSBACHER KENNETH J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O XENOPORT, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>3410 CENTRAL EXPRESSWAY</rptOwnerStreet2>
            <rptOwnerCity>SANTA CLARA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95051</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>10.39</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-06-02</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-06-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The option becomes exercisable on June 2, 2006.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Kenneth J. Nussbacher</signatureName>
        <signatureDate>2005-06-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----