-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 UkG6ohy9xnyDVpVelTpu4XHH28vqeHpqxQhMTVVYycpD47UNmjqUKERa7di2rG+w
 Z/5pt7LFStUZ3znEuTUrWw==

<SEC-DOCUMENT>0001485000-10-000002.txt : 20100303
<SEC-HEADER>0001485000-10-000002.hdr.sgml : 20100303
<ACCEPTANCE-DATETIME>20100303130412
ACCESSION NUMBER:		0001485000-10-000002
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100302
FILED AS OF DATE:		20100303
DATE AS OF CHANGE:		20100303

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MERWIN BRIAN
		CENTRAL INDEX KEY:			0001485000

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-51826
		FILM NUMBER:		10652464

	MAIL ADDRESS:	
		STREET 1:		SUITE 2840
		STREET 2:		650 WEST GEORGIA STREET
		CITY:			VANCOUVER
		STATE:			A1
		ZIP:			V6B 4N8

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MERCER INTERNATIONAL INC.
		CENTRAL INDEX KEY:			0001333274
		STANDARD INDUSTRIAL CLASSIFICATION:	PULP MILLS [2611]
		IRS NUMBER:				470956945
		STATE OF INCORPORATION:			WA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		14900 INTERURBAN AVENUE SOUTH
		STREET 2:		SUITE 282
		CITY:			SEATTLE
		STATE:			WA
		ZIP:			98168
		BUSINESS PHONE:		(206) 674-4639

	MAIL ADDRESS:	
		STREET 1:		14900 INTERURBAN AVENUE SOUTH
		STREET 2:		SUITE 282
		CITY:			SEATTLE
		STATE:			WA
		ZIP:			98168

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MERCER INTERNATIONAL REGCO INC.
		DATE OF NAME CHANGE:	20050715
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-03-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001333274</issuerCik>
        <issuerName>MERCER INTERNATIONAL INC.</issuerName>
        <issuerTradingSymbol>MERC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001485000</rptOwnerCik>
            <rptOwnerName>MERWIN BRIAN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SUITE 2840</rptOwnerStreet1>
            <rptOwnerStreet2>650 WEST GEORGIA STREET</rptOwnerStreet2>
            <rptOwnerCity>VANCOUVER</rptOwnerCity>
            <rptOwnerState>A1</rptOwnerState>
            <rptOwnerZipCode>V6B 4N8</rptOwnerZipCode>
            <rptOwnerStateDescription>BRITISH COLUMBIA, CANADA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP Strategic Initiatives</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2010-03-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>7300</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.06</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11900</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>/s/ Brian Merwin</signatureName>
        <signatureDate>2010-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----