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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 Q/HmotEYP3EdNOI3A+hDAdt9+rR0Rpr4ufVq/vvsN8RvAuwQewPhnkqpfz6dt/EQ
 xGVVzdHIHVFWjonFj3fzVQ==

<SEC-DOCUMENT>0001112799-09-000002.txt : 20090108
<SEC-HEADER>0001112799-09-000002.hdr.sgml : 20090108
<ACCEPTANCE-DATETIME>20090108202205
ACCESSION NUMBER:		0001112799-09-000002
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20081229
FILED AS OF DATE:		20090108
DATE AS OF CHANGE:		20090108

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Marshall Dennis E
		CENTRAL INDEX KEY:			0001361115

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-19709
		FILM NUMBER:		09516796

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		949 235-8062

	MAIL ADDRESS:	
		STREET 1:		2603 MAIN STREET SUITE 1150
		CITY:			IRVINE
		STATE:			CA
		ZIP:			92614

	FORMER NAME:	
		FORMER CONFORMED NAME:	Marshall Dennis
		DATE OF NAME CHANGE:	20060428

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BIOLARGO, INC.
		CENTRAL INDEX KEY:			0000880242
		STANDARD INDUSTRIAL CLASSIFICATION:	CHEMICALS & ALLIED PRODUCTS [2800]
		IRS NUMBER:				650159115
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2603 MAIN ST.
		STREET 2:		SUITE 1155
		CITY:			IRVINE
		STATE:			CA
		ZIP:			92614
		BUSINESS PHONE:		949-643-9540

	MAIL ADDRESS:	
		STREET 1:		2603 MAIN ST.
		STREET 2:		SUITE 1155
		CITY:			IRVINE
		STATE:			CA
		ZIP:			92614

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NUWAY MEDICAL INC
		DATE OF NAME CHANGE:	20030205

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NUWAY ENERGY INC
		DATE OF NAME CHANGE:	20010815

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	LATIN AMERICAN CASINOS INC
		DATE OF NAME CHANGE:	19960520
</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>2008-12-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000880242</issuerCik>
        <issuerName>BIOLARGO, INC.</issuerName>
        <issuerTradingSymbol>blgo</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001361115</rptOwnerCik>
            <rptOwnerName>Marshall Dennis E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2603 MAIN STREET SUITE 1155</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>IRVINE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92614</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>2008-12-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>33898</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.59</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>188603</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Reporting Person as Trustee for the Dennis &amp; Cathy Marshall Family Trust DTD 6/21/07</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares were issued to the Reporting Person in payment of $20,000 of non-employee directors' fees owed to him by the Issuer.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Dennis E. Marshall</signatureName>
        <signatureDate>2009-01-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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