-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 VJb+Kb3ydc6GRwCwe4msWw==

<SEC-DOCUMENT>0001378637-09-000006.txt : 20090313
<SEC-HEADER>0001378637-09-000006.hdr.sgml : 20090313
<ACCEPTANCE-DATETIME>20090313111506
ACCESSION NUMBER:		0001378637-09-000006
CONFORMED SUBMISSION TYPE:	D
PUBLIC DOCUMENT COUNT:		1
ITEM INFORMATION:		Rule 506
FILED AS OF DATE:		20090313
DATE AS OF CHANGE:		20090313
EFFECTIVENESS DATE:		20090313

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MFS Institutional Money Market Portfolio, a series of the MFS Series Trust XIV
		CENTRAL INDEX KEY:			0001392417
		IRS NUMBER:				208538605
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			0831

	FILING VALUES:
		FORM TYPE:		D
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	021-127847
		FILM NUMBER:		09678193

	BUSINESS ADDRESS:	
		STREET 1:		500 BOYLSTON STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		617-954-5000

	MAIL ADDRESS:	
		STREET 1:		500 BOYLSTON STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MFS Series Trust XIV
		DATE OF NAME CHANGE:	20070308
</SEC-HEADER>
<DOCUMENT>
<TYPE>D
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<edgarSubmission>

    <schemaVersion>X0201</schemaVersion>

    <submissionType>D</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0001392417</cik>
        <entityName>MFS Institutional Money Market Portfolio, a series of the MFS Series Trust XIV</entityName>
        <issuerAddress>
            <street1>500 BOYLSTON STREET</street1>
            <street2></street2>
            <city>BOSTON</city>
            <stateOrCountry>MA</stateOrCountry>
            <zipCode>02116</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>617-954-5000</issuerPhoneNumber>
        <issuerPreviousNameList>
            <previousName>MFS Series Trust XIV</previousName>
        </issuerPreviousNameList>
        <jurisdictionOfInc>MA</jurisdictionOfInc>
        <entityType>Business Trust</entityType>
        <yearOfInc>
            <withinFiveYears>true</withinFiveYears>
            <value>2007</value>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Robert</firstName>
                <middleName>C.</middleName>
                <lastName>Pozen</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Robert</firstName>
                <middleName>J.</middleName>
                <lastName>Manning</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
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            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>J. Atwood</firstName>
                <middleName></middleName>
                <lastName>Ives</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Robert</firstName>
                <middleName>E.</middleName>
                <lastName>Butler</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Lawrence</firstName>
                <middleName></middleName>
                <lastName>Cohn</lastName>
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            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
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            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>David</firstName>
                <middleName>H.</middleName>
                <lastName>Gunning</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>William</firstName>
                <middleName>R.</middleName>
                <lastName>Gutow</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Michael</firstName>
                <middleName></middleName>
                <lastName>Hegarty</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>J. Dale</firstName>
                <middleName></middleName>
                <lastName>Sherratt</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Laurie</firstName>
                <middleName>J.</middleName>
                <lastName>Thomsen</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Robert</firstName>
                <middleName>W.</middleName>
                <lastName>Uek</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>John</firstName>
                <middleName>P.</middleName>
                <lastName>Kavanaugh</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Maureen</firstName>
                <middleName>F.</middleName>
                <lastName>Goldfarb</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Maria</firstName>
                <middleName></middleName>
                <lastName>Dwyer</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>President</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>John</firstName>
                <middleName>C.</middleName>
                <lastName>Corcoran</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>Treasurer</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Mark</firstName>
                <middleName></middleName>
                <lastName>Polebaum</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>500 Boylston Street</street1>
                <street2></street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>Secretary and Clerk</relationshipClarification>
        </relatedPersonInfo>
    </relatedPersonsList>

    <offeringData>
        <industryGroup>
            <industryGroupType>Pooled Investment Fund</industryGroupType>
            <investmentFundInfo>
                <investmentFundType>Other Investment Fund</investmentFundType>
                <is40Act>true</is40Act>
            </investmentFundInfo>
        </industryGroup>
        <issuerSize>
            <aggregateNetAssetValueRange>Decline to Disclose</aggregateNetAssetValueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>false</isAmendment>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>2007-03-19</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>true</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isPooledInvestmentFundType>true</isPooledInvestmentFundType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>0</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>Indefinite</totalOfferingAmount>
            <totalAmountSold>0</totalAmountSold>
            <totalRemaining>Indefinite</totalRemaining>
            <clarificationOfResponse>The issuer is an open-end fund investment company and its net assets may vary on a daly basis.</clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>112</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>0</dollarAmount>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
            </findersFees>
            <clarificationOfResponse></clarificationOfResponse>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>0</dollarAmount>
            </grossProceedsUsed>
            <clarificationOfResponse></clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>MFS Institutional Money Market Portfolio, a series of the MFS Series Trust XIV</issuerName>
                <signatureName>/s/ Susan A. Pereira</signatureName>
                <nameOfSigner>Susan A. Pereira</nameOfSigner>
                <signatureTitle>Assistant Secretary and Assistant Clerk</signatureTitle>
                <signatureDate>2009-03-13</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----