<?xml version="1.0"?>
<edgarSubmission>

    <schemaVersion>X0704</schemaVersion>

    <submissionType>D/A</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0001467141</cik>
        <entityName>GAM US Institutional Trading II Inc.</entityName>
        <issuerAddress>
            <street1>GEORGE'S COURT, 54-62 TOWNSEND STREET</street1>
            <city>DUBLIN 2</city>
            <stateOrCountry>L2</stateOrCountry>
            <stateOrCountryDescription>IRELAND</stateOrCountryDescription>
            <zipCode>00000</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>353 (0) 1 609 3900</issuerPhoneNumber>
        <jurisdictionOfInc>VIRGIN ISLANDS, BRITISH</jurisdictionOfInc>
        <issuerPreviousNameList>
            <value>None</value>
        </issuerPreviousNameList>
        <edgarPreviousNameList>
            <value>None</value>
        </edgarPreviousNameList>
        <entityType>Corporation</entityType>
        <yearOfInc>
            <yetToBeFormed>true</yetToBeFormed>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Andrew</firstName>
                <lastName>Hanges</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>12 St. James's Place</street1>
                <city>London</city>
                <stateOrCountry>X0</stateOrCountry>
                <stateOrCountryDescription>UNITED KINGDOM</stateOrCountryDescription>
                <zipCode>SW1A 1NX</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Jozef</firstName>
                <lastName>Hendriks</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>Thistle House</street1>
                <street2>4 Burnaby Street</street2>
                <city>Hamilton HM11</city>
                <stateOrCountry>D0</stateOrCountry>
                <stateOrCountryDescription>BERMUDA</stateOrCountryDescription>
                <zipCode>00000</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Maxwell</firstName>
                <lastName>Quin</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>52 Reid Street</street1>
                <street2>P.O. Box 1737</street2>
                <city>Hamilton</city>
                <stateOrCountry>D0</stateOrCountry>
                <stateOrCountryDescription>BERMUDA</stateOrCountryDescription>
                <zipCode>00000</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
    </relatedPersonsList>

    <offeringData>
        <industryGroup>
            <industryGroupType>Pooled Investment Fund</industryGroupType>
            <investmentFundInfo>
                <investmentFundType>Other Investment Fund</investmentFundType>
                <is40Act>false</is40Act>
            </investmentFundInfo>
        </industryGroup>
        <issuerSize>
            <aggregateNetAssetValueRange>Decline to Disclose</aggregateNetAssetValueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>true</isAmendment>
                <previousAccessionNumber>0001467141-09-000001</previousAccessionNumber>
            </newOrAmendment>
            <dateOfFirstSale>
                <yetToOccur>true</yetToOccur>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>true</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isPooledInvestmentFundType>true</isPooledInvestmentFundType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>5000000</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>Indefinite</totalOfferingAmount>
            <totalAmountSold>0</totalAmountSold>
            <totalRemaining>Indefinite</totalRemaining>
            <clarificationOfResponse></clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>0</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>0</dollarAmount>
                <isEstimate>true</isEstimate>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
                <isEstimate>true</isEstimate>
            </findersFees>
            <clarificationOfResponse></clarificationOfResponse>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>0</dollarAmount>
                <isEstimate>true</isEstimate>
            </grossProceedsUsed>
            <clarificationOfResponse></clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>GAM US Institutional Trading II Inc.</issuerName>
                <signatureName>/s/ Michael Whooley</signatureName>
                <nameOfSigner>Michael Whooley</nameOfSigner>
                <signatureTitle>Director of Administrator</signatureTitle>
                <signatureDate>2010-11-19</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>
