<SEC-DOCUMENT>0001209191-19-010158.txt : 20190214
<SEC-HEADER>0001209191-19-010158.hdr.sgml : 20190214
<ACCEPTANCE-DATETIME>20190214162744
ACCESSION NUMBER:		0001209191-19-010158
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190212
FILED AS OF DATE:		20190214
DATE AS OF CHANGE:		20190214

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ALVAREZ CESAR L
		CENTRAL INDEX KEY:			0001220297

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12111
		FILM NUMBER:		19606937

	MAIL ADDRESS:	
		STREET 1:		C/O PEDIATRIX MEDICAL GROUP
		STREET 2:		LEGAL DEPT 1301- CONCORD TERRACE
		CITY:			SUNRISE
		STATE:			FL
		ZIP:			33323

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MEDNAX, INC.
		CENTRAL INDEX KEY:			0000893949
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-HOSPITALS [8060]
		IRS NUMBER:				263667538
		STATE OF INCORPORATION:			FL
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1301 CONCORD TERRACE
		CITY:			SUNRISE
		STATE:			FL
		ZIP:			33323
		BUSINESS PHONE:		9543840175

	MAIL ADDRESS:	
		STREET 1:		1301 CONCORD TERRACE
		CITY:			SUNRISE
		STATE:			FL
		ZIP:			33323

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	PEDIATRIX MEDICAL GROUP INC
		DATE OF NAME CHANGE:	19950801
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-02-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000893949</issuerCik>
        <issuerName>MEDNAX, INC.</issuerName>
        <issuerTradingSymbol>MD</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001220297</rptOwnerCik>
            <rptOwnerName>ALVAREZ CESAR L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1301 CONCORD TERRACE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SUNRISE</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>33323</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-02-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3699</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>43686</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Restricted shares granted pursuant to Issuer's Amended and Restated 2008 Incentive Compensation Plan, as amended, in connection with annual equity award.  Shares will vest in three equal installments on March 1, 2020, March 1, 2021 and March 1, 2022.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Dominic J. Andreano, Attorney-in-Fact</signatureName>
        <signatureDate>2019-02-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
