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

    <schemaVersion>X0706</schemaVersion>

    <submissionType>D/A</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0001528382</cik>
        <entityName>Omega Fund IV, L.P.</entityName>
        <issuerAddress>
            <street1>1 ROYAL PLAZA, ROYAL AVENUE</street1>
            <city>ST. PETER PORT</city>
            <stateOrCountry>Y7</stateOrCountry>
            <stateOrCountryDescription>GUERNSEY</stateOrCountryDescription>
            <zipCode>GY1 2HL</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>44 0 148 173 5806</issuerPhoneNumber>
        <jurisdictionOfInc>CAYMAN ISLANDS</jurisdictionOfInc>
        <issuerPreviousNameList>
            <previousName>Life Sciences Holdings SPV II Fund, LP</previousName>
        </issuerPreviousNameList>
        <edgarPreviousNameList>
            <value>None</value>
        </edgarPreviousNameList>
        <entityType>Other</entityType>
        <entityTypeOtherDesc>Cayman Islands exempted limited partnership</entityTypeOtherDesc>
        <yearOfInc>
            <withinFiveYears>true</withinFiveYears>
            <value>2010</value>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>N/A</firstName>
                <lastName>Omega Fund IV GP, L.P.</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>1 Royal Plaza, Royal Avenue</street1>
                <street2>Channel Islands</street2>
                <city>St. Peter Port</city>
                <stateOrCountry>Y7</stateOrCountry>
                <stateOrCountryDescription>GUERNSEY</stateOrCountryDescription>
                <zipCode>GY1 2HL</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>General Partner to the Issuer</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>N/A</firstName>
                <lastName>Omega Fund IV GP Manager, Ltd.</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>1 Royal Plaza, Royal Avenue</street1>
                <street2>Channel Islands</street2>
                <city>St. Peter Port</city>
                <stateOrCountry>Y7</stateOrCountry>
                <stateOrCountryDescription>GUERNSEY</stateOrCountryDescription>
                <zipCode>GY1 2HL</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>The General Partner of the General Partner to the Issuer (GP LTD)</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>N/A</firstName>
                <lastName>Omega Fund Management Limited</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>1 Royal Plaza, Royal Avenue</street1>
                <street2>Channel Islands</street2>
                <city>St. Peter Port</city>
                <stateOrCountry>Y7</stateOrCountry>
                <stateOrCountryDescription>GUERNSEY</stateOrCountryDescription>
                <zipCode>GY1 2HL</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>Management Company to the Issuer</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Mr. Otello</firstName>
                <lastName>Stampacchia</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Alpha Biotechnology Consulting FZE</street1>
                <street2>P.O. Box 186549</street2>
                <city>Dubai</city>
                <stateOrCountry>C0</stateOrCountry>
                <stateOrCountryDescription>UNITED ARAB EMIRATES</stateOrCountryDescription>
                <zipCode>000000</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>A Director of GP LTD</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Mr. Richard</firstName>
                <lastName>Lim</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>545 Boylston Street, Suite 802</street1>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <stateOrCountryDescription>MASSACHUSETTS</stateOrCountryDescription>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>A Director of GP LTD</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Ms. Renee</firstName>
                <lastName>Aguiar-Lucander</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>32 Old Burlington Street</street1>
                <city>London</city>
                <stateOrCountry>X0</stateOrCountry>
                <stateOrCountryDescription>UNITED KINGDOM</stateOrCountryDescription>
                <zipCode>W1S 3AT</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>A Director of GP LTD</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Ms. Anne-Mari</firstName>
                <lastName>Paster</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>545 Boylston Street, Suite 802</street1>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <stateOrCountryDescription>MASSACHUSETTS</stateOrCountryDescription>
                <zipCode>02116</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>A Director of GP LTD</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>
            <item>3C</item>
            <item>3C.7</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>true</isAmendment>
                <previousAccessionNumber>0001528382-13-000001</previousAccessionNumber>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>2011-08-26</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>true</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isPooledInvestmentFundType>true</isPooledInvestmentFundType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>0</minimumInvestmentAccepted>
        <salesCompensationList>
            <recipient>
                <recipientName>Harken Capital Securities LLC</recipientName>
                <recipientCRDNumber>163749</recipientCRDNumber>
                <associatedBDName>None</associatedBDName>
                <associatedBDCRDNumber>None</associatedBDCRDNumber>
                <recipientAddress>
                    <street1>16 Ann Vinal Road</street1>
                    <city>Scituate</city>
                    <stateOrCountry>MA</stateOrCountry>
                    <stateOrCountryDescription>MASSACHUSETTS</stateOrCountryDescription>
                    <zipCode>02066</zipCode>
                </recipientAddress>
                <statesOfSolicitationList>
                    <state>UT</state>
                    <description>UTAH</description>
                    <state>IL</state>
                    <description>ILLINOIS</description>
                    <state>NY</state>
                    <description>NEW YORK</description>
                    <state>CT</state>
                    <description>CONNECTICUT</description>
                    <state>GA</state>
                    <description>GEORGIA</description>
                    <state>DC</state>
                    <description>DISTRICT OF COLUMBIA</description>
                    <state>MN</state>
                    <description>MINNESOTA</description>
                    <state>CA</state>
                    <description>CALIFORNIA</description>
                    <state>MO</state>
                    <description>MISSOURI</description>
                    <state>ME</state>
                    <description>MAINE</description>
                    <state>VA</state>
                    <description>VIRGINIA</description>
                    <state>NJ</state>
                    <description>NEW JERSEY</description>
                    <state>OH</state>
                    <description>OHIO</description>
                    <state>TX</state>
                    <description>TEXAS</description>
                    <state>CO</state>
                    <description>COLORADO</description>
                    <state>FL</state>
                    <description>FLORIDA</description>
                    <state>PA</state>
                    <description>PENNSYLVANIA</description>
                    <state>NC</state>
                    <description>NORTH CAROLINA</description>
                    <state>MD</state>
                    <description>MARYLAND</description>
                    <state>MA</state>
                    <description>MASSACHUSETTS</description>
                </statesOfSolicitationList>
                <foreignSolicitation>false</foreignSolicitation>
            </recipient>
            <recipient>
                <recipientName>Farrell Marsh &amp; Co.</recipientName>
                <recipientCRDNumber>31971</recipientCRDNumber>
                <associatedBDName>None</associatedBDName>
                <associatedBDCRDNumber>None</associatedBDCRDNumber>
                <recipientAddress>
                    <street1>500 The Times Building, Suburban Square</street1>
                    <city>Ardmore</city>
                    <stateOrCountry>PA</stateOrCountry>
                    <stateOrCountryDescription>PENNSYLVANIA</stateOrCountryDescription>
                    <zipCode>19003</zipCode>
                </recipientAddress>
                <statesOfSolicitationList>
                    <state>RI</state>
                    <description>RHODE ISLAND</description>
                    <state>NY</state>
                    <description>NEW YORK</description>
                    <state>GA</state>
                    <description>GEORGIA</description>
                    <state>CA</state>
                    <description>CALIFORNIA</description>
                    <state>VA</state>
                    <description>VIRGINIA</description>
                    <state>MI</state>
                    <description>MICHIGAN</description>
                    <state>OH</state>
                    <description>OHIO</description>
                    <state>DE</state>
                    <description>DELAWARE</description>
                    <state>IA</state>
                    <description>IOWA</description>
                    <state>FL</state>
                    <description>FLORIDA</description>
                    <state>MD</state>
                    <description>MARYLAND</description>
                    <state>MA</state>
                    <description>MASSACHUSETTS</description>
                    <state>SC</state>
                    <description>SOUTH CAROLINA</description>
                    <state>IL</state>
                    <description>ILLINOIS</description>
                    <state>IN</state>
                    <description>INDIANA</description>
                    <state>CT</state>
                    <description>CONNECTICUT</description>
                    <state>DC</state>
                    <description>DISTRICT OF COLUMBIA</description>
                    <state>MN</state>
                    <description>MINNESOTA</description>
                    <state>WI</state>
                    <description>WISCONSIN</description>
                    <state>KY</state>
                    <description>KENTUCKY</description>
                    <state>AZ</state>
                    <description>ARIZONA</description>
                    <state>MO</state>
                    <description>MISSOURI</description>
                    <state>MT</state>
                    <description>MONTANA</description>
                    <state>NJ</state>
                    <description>NEW JERSEY</description>
                    <state>NM</state>
                    <description>NEW MEXICO</description>
                    <state>TX</state>
                    <description>TEXAS</description>
                    <state>CO</state>
                    <description>COLORADO</description>
                    <state>NC</state>
                    <description>NORTH CAROLINA</description>
                    <state>PA</state>
                    <description>PENNSYLVANIA</description>
                </statesOfSolicitationList>
                <foreignSolicitation>false</foreignSolicitation>
            </recipient>
        </salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>250000000</totalOfferingAmount>
            <totalAmountSold>181875000</totalAmountSold>
            <totalRemaining>68125000</totalRemaining>
            <clarificationOfResponse></clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>34</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>0</dollarAmount>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
            </findersFees>
            <clarificationOfResponse></clarificationOfResponse>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>0</dollarAmount>
            </grossProceedsUsed>
            <clarificationOfResponse>The Issuer is obligated to pay a management fee to the General Partner (or affiliates thereof).</clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>Omega Fund IV, L.P.</issuerName>
                <signatureName>/s/ Anne-Mari Paster</signatureName>
                <nameOfSigner>Anne-Mari Paster</nameOfSigner>
                <signatureTitle>A Director of Omega Fund IV GP Manager, Ltd.</signatureTitle>
                <signatureDate>2013-05-24</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>