<SEC-DOCUMENT>0001562180-20-005448.txt : 20200814
<SEC-HEADER>0001562180-20-005448.hdr.sgml : 20200814
<ACCEPTANCE-DATETIME>20200814182713
ACCESSION NUMBER:		0001562180-20-005448
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20200127
FILED AS OF DATE:		20200814
DATE AS OF CHANGE:		20200814

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Skyline Venture Management V, LLC
		CENTRAL INDEX KEY:			0001434887
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38701
		FILM NUMBER:		201107153

	BUSINESS ADDRESS:	
		STREET 1:		525 UNIVERSITY AVENUE
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94301
		BUSINESS PHONE:		650-475-0144

	MAIL ADDRESS:	
		STREET 1:		525 UNIVERSITY AVENUE
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94301

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Freund John Gordon
		CENTRAL INDEX KEY:			0001296771

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38701
		FILM NUMBER:		201107154

	MAIL ADDRESS:	
		STREET 1:		125 UNIVERSITY AVE.
		STREET 2:		C/O SKYLINE VENTURES
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94301

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Skyline Venture Partners V LP
		CENTRAL INDEX KEY:			0001419187
		STATE OF INCORPORATION:			DE

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38701
		FILM NUMBER:		201107155

	BUSINESS ADDRESS:	
		STREET 1:		525 University Avenue
		STREET 2:		Suite 520
		CITY:			Palo Alto
		STATE:			CA
		ZIP:			94301

	MAIL ADDRESS:	
		STREET 1:		525 University Avenue
		STREET 2:		Suite 520
		CITY:			Palo Alto
		STATE:			CA
		ZIP:			94301

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SI-BONE, Inc.
		CENTRAL INDEX KEY:			0001459839
		STANDARD INDUSTRIAL CLASSIFICATION:	SURGICAL & MEDICAL INSTRUMENTS & APPARATUS [3841]
		IRS NUMBER:				262216351
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		471 EL CAMINO REAL, SUITE 101
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95050
		BUSINESS PHONE:		4082070700

	MAIL ADDRESS:	
		STREET 1:		471 EL CAMINO REAL, SUITE 101
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95050

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	SI-Bone Inc.
		DATE OF NAME CHANGE:	20090326
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primarydocument.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-01-27</periodOfReport>

    <notSubjectToSection16>false</notSubjectToSection16>

    <issuer>
        <issuerCik>0001459839</issuerCik>
        <issuerName>SI-BONE, Inc.</issuerName>
        <issuerTradingSymbol>SIBN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001419187</rptOwnerCik>
            <rptOwnerName>Skyline Venture Partners V LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>525 UNIVERSITY AVENUE, SUITE 1350</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94301</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>true</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001296771</rptOwnerCik>
            <rptOwnerName>Freund John Gordon</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SKYLINE VENTURES</rptOwnerStreet1>
            <rptOwnerStreet2>525 UNIVERSITY AVENUE, SUITE 1350</rptOwnerStreet2>
            <rptOwnerCity>PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94301</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>true</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001434887</rptOwnerCik>
            <rptOwnerName>Skyline Venture Management V, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>525 UNIVERSITY AVENUE, SUITE 1350</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94301</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>true</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-01-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000000.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>21.50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2819985.00</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Skyline Venture Partners V, LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Shares are sold in the conjunction with SI-BONE, INC's public offering of common stock announced on January 21st, 2020.</footnote>
        <footnote id="F2">Shares held by Skyline Venture Partners V, L.P. (&quot;SVP V&quot;). Skyline Venture Management V, LLC (&quot;LLC&quot;) is the general partner of SVP V and as such may be deemed to have voting and investment power with respect to the securities of SVP V. Dr. Freund, a member of the Issuer's board of directors, is a managing director of LLC and may be deemed to have voting and investment power with respect to the securities held by SVP V. Dr. Freund disclaims beneficial ownership of such securities, except to the extent of his pecuniary interest therein. Although each of SVP V and LLC have ceased to be subject to the reporting requirements of Section 16 as a result of this sale of shares and the public offering, Dr. Freund is a director of SI-BONE, Inc. and, accordingly, remains subject to the reporting requirements of Section 16.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Skyline Venture Partners V, L.P., By: Skyline Venture Management V, LLC, Its: General Partner, By: /s/ Michael A. Pisetsky , Attorney-in-Fact</signatureName>
        <signatureDate>2020-08-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Michael A. Pisetsky, Attorney-in-Fact for John G. Freund</signatureName>
        <signatureDate>2020-08-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Skyline Venture Management V, LLC, By: /s/ Michael A. Pisetsky, Attorney-in-Fact</signatureName>
        <signatureDate>2020-08-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
