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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2016-10-19</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001388658</issuerCik>
        <issuerName>iRhythm Technologies, Inc.</issuerName>
        <issuerTradingSymbol>IRTC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001441439</rptOwnerCik>
            <rptOwnerName>New Leaf Ventures II, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEW LEAF VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>7 TIMES SQUARE, SUITE 3502</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001441563</rptOwnerCik>
            <rptOwnerName>Delagardelle Jeani</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEW LEAF VENTURE PARTNERS,</rptOwnerStreet1>
            <rptOwnerStreet2>1200 PARK PLACE, SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>SAN MATEO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94403</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001247851</rptOwnerCik>
            <rptOwnerName>HUNT RONALD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEW LEAF VENTURE PARTNERS,</rptOwnerStreet1>
            <rptOwnerStreet2>7 TIMES SQUARE, SUITE 3502</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001547100</rptOwnerCik>
            <rptOwnerName>Ratcliffe Liam</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEW LEAF VENTURE PARTNERS,</rptOwnerStreet1>
            <rptOwnerStreet2>7 TIMES SQUARE, SUITE 3502</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001441858</rptOwnerCik>
            <rptOwnerName>New Leaf Venture Associates II, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEW LEAF VENTURE PARTNERS,</rptOwnerStreet1>
            <rptOwnerStreet2>7 TIMES SQUARE, SUITE 3502</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001441857</rptOwnerCik>
            <rptOwnerName>New Leaf Venture Management II, L.L.C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEW LEAF VENTURE PARTNERS,</rptOwnerStreet1>
            <rptOwnerStreet2>7 TIMES SQUARE, SUITE 3502</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001192212</rptOwnerCik>
            <rptOwnerName>Chambon Philippe O.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEW LEAF VENTURE PARTNERS,</rptOwnerStreet1>
            <rptOwnerStreet2>7 TIMES SQUARE, SUITE 3502</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Series C Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1794624</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series C Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1794623</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series D Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1118623</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series E Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>670736</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series E Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>244311</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series D Preferred Stock Warrant (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.001</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2019-11-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>425847</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Immediately</footnote>
        <footnote id="F2">N/A</footnote>
        <footnote id="F3">The number of underlying shares of common stock reported in column 3 does not reflect a 5.882698 for 1 reverse stock split, to be effective upon the closing of the issuer's initial public offering.</footnote>
        <footnote id="F4">Converts into common stock on a 2.24685484 for 1 basis.</footnote>
        <footnote id="F5">Represents shares directly beneficially owned by New Leaf Ventures II, L.P. (&quot;NLV II&quot;). New Leaf Venture Associates II, L.P. (&quot;NLV Associates II&quot;) is the general partner of NLV II and New Leaf Venture Management II, L.L.C. (&quot;NLV Management II&quot;) is the general partner of NLV Associates II. Philippe O. Chambon, Jeani Delagardelle, Ronald Hunt, Vijay Lathi and Liam Ratcliffe are the individual managers of NLV Management II (the &quot;Individual Managers&quot;). NLV Associates II and NLV Management II disclaim beneficial ownership of such shares, except to the extent of their pecuniary interest therein. Vijay Lathi is a director of the Issuer and, accordingly, files separate Section 16 reports. As one of five individual managers, each of the Individual Managers disclaims beneficial ownership over the shares reported herein, and in all events disclaims pecuniary interest except to the extent of his or her economic interest.</footnote>
        <footnote id="F6">1-for-1</footnote>
    </footnotes>

    <remarks>EXHIBIT LIST
Exhibit 24
Exhibit 99

The Date of Event is based upon the date of effectiveness of the Issuer's Registration Statement on Form S-1 filed in connection with the Issuer's initial public offering, estimated to be on or about October 19, 2016.</remarks>

    <ownerSignature>
        <signatureName>/s/ Craig L. Slutzkin, attorney-in-fact for New Leaf Venture Management II, L.L.C., the sole general partner of New Leaf Venture Associates II, L.P., the sole general partner of New Leaf Ventures II, L.P.</signatureName>
        <signatureDate>2016-10-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Craig L. Slutzkin, attorney-in-fact for New Leaf Venture Management II, L.L.C., the sole general partner of New Leaf Venture Associates II, L.P.</signatureName>
        <signatureDate>2016-10-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Craig L. Slutzkin, attorney-in-fact for New Leaf Venture Management II, L.L.C.</signatureName>
        <signatureDate>2016-10-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Craig L. Slutzkin, attorney-in-fact for Philippe O. Chambon</signatureName>
        <signatureDate>2016-10-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Craig L. Slutzkin, attorney-in-fact for Jeani Delagardelle</signatureName>
        <signatureDate>2016-10-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Craig L. Slutzkin, attorney-in-fact for Ronald M. Hunt</signatureName>
        <signatureDate>2016-10-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Craig L. Slutzkin, attorney-in-fact for Liam Ratcliffe</signatureName>
        <signatureDate>2016-10-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
