<?xml version="1.0" encoding="us-ascii"?>
<!--XBRL document created by RR Donnelley IM Processor 6.0.0.0 using Fujitsu Interstage XWand-->
<schema targetNamespace="http://www.janus.com/20121210" elementFormDefault="qualified" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:jif4="http://www.janus.com/20121210" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric">
  <annotation>
    <appinfo>
      <link:linkbaseRef xlink:type="simple" xlink:href="jif4-20121210_pre.xml" xlink:title="Presentation Links, all" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="jif4-20121210_cal.xml" xlink:title="Calculation Links, all" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="jif4-20121210_def.xml" xlink:title="Definition Links, all" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="jif4-20121210_lab.xml" xlink:title="Label Links, all" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:roleType roleURI="http://www.janus.com/role/DocumentDocumentandEntityInformation" id="DocumentDocumentandEntityInformation">
        <link:definition>000000 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/DocumentRiskReturnSupplementUnlabeledJANUSINVESTMENTFUND" id="DocumentRiskReturnSupplementUnlabeledJANUSINVESTMENTFUND">
        <link:definition>000010 - Document - Risk/Return Supplement {Unlabeled} - JANUS INVESTMENT FUND</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/DocumentRiskReturnSummaryUnlabeledJanusGrowthAllocationFund" id="DocumentRiskReturnSummaryUnlabeledJanusGrowthAllocationFund">
        <link:definition>000011 - Document - Risk/Return Summary {Unlabeled} - Janus Growth Allocation Fund</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/ScheduleShareholderFeesJanusGrowthAllocationFund" id="ScheduleShareholderFeesJanusGrowthAllocationFund">
        <link:definition>000012 - Schedule - Shareholder Fees {- Janus Growth Allocation Fund}</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/ScheduleAnnualFundOperatingExpensesJanusGrowthAllocationFund" id="ScheduleAnnualFundOperatingExpensesJanusGrowthAllocationFund">
        <link:definition>000013 - Schedule - Annual Fund Operating Expenses {- Janus Growth Allocation Fund}</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/ScheduleExpenseExampleTransposedJanusGrowthAllocationFund" id="ScheduleExpenseExampleTransposedJanusGrowthAllocationFund">
        <link:definition>000014 - Schedule - Expense Example {Transposed} {- Janus Growth Allocation Fund}</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/ScheduleExpenseExampleNoRedemptionTransposedJanusGrowthAllocationFund" id="ScheduleExpenseExampleNoRedemptionTransposedJanusGrowthAllocationFund">
        <link:definition>000015 - Schedule - Expense Example, No Redemption {Transposed} {- Janus Growth Allocation Fund}</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/ScheduleAnnualTotalReturnsJanusGrowthAllocationFundBarChart" id="ScheduleAnnualTotalReturnsJanusGrowthAllocationFundBarChart">
        <link:definition>000016 - Schedule - Annual Total Returns - Janus Growth Allocation Fund [BarChart]</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/ScheduleAverageAnnualTotalReturnsTransposedJanusGrowthAllocationFund" id="ScheduleAverageAnnualTotalReturnsTransposedJanusGrowthAllocationFund">
        <link:definition>000017 - Schedule - Average Annual Total Returns {Transposed} {- Janus Growth Allocation Fund}</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/DocumentRiskReturnDetailUnlabeledJanusGrowthAllocationFund" id="DocumentRiskReturnDetailUnlabeledJanusGrowthAllocationFund">
        <link:definition>000018 - Document - Risk/Return Detail {Unlabeled} - Janus Growth Allocation Fund</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.janus.com/role/DisclosureRiskReturnDetailDataElementsJANUSINVESTMENTFUND" id="DisclosureRiskReturnDetailDataElementsJANUSINVESTMENTFUND">
        <link:definition>000019 - Disclosure - Risk/Return Detail Data {Elements} - JANUS INVESTMENT FUND</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </appinfo>
  </annotation>
  <import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" />
  <import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" />
  <import namespace="http://xbrl.sec.gov/dei/2012-01-31" schemaLocation="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd" />
  <import namespace="http://xbrl.sec.gov/rr/2012-01-31" schemaLocation="http://xbrl.sec.gov/rr/2012/rr-2012-01-31.xsd" />
  <import namespace="http://www.xbrl.org/dtr/type/non-numeric" schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" />
  <element name="SupplementTextBlock" id="jif4_SupplementTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="S000010481Member" id="jif4_S000010481Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000077710Member" id="jif4_C000077710Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000077711Member" id="jif4_C000077711Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000083527Member" id="jif4_C000083527Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000077712Member" id="jif4_C000077712Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000077713Member" id="jif4_C000077713Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000028941Member" id="jif4_C000028941Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="JanusConservativeAllocationFundMember" id="jif4_JanusConservativeAllocationFundMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="JanusModerateAllocationFundMember" id="jif4_JanusModerateAllocationFundMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="ClassDSharesMember" id="jif4_ClassDSharesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="ClassAcsitSharesMember" id="jif4_ClassAcsitSharesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
</schema>
