-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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MIC-Info: RSA-MD5,RSA,
 J9ZesepxKiAcvypumVXADr4zsaw6l08Ujvo+65tdeJhoeXX4wdKViKxJTmYqeZoF
 JkrnCrLt0pM2saqno7L0BA==

<SEC-DOCUMENT>0001240147-04-000001.txt : 20040422
<SEC-HEADER>0001240147-04-000001.hdr.sgml : 20040422
<ACCEPTANCE-DATETIME>20040422131448
ACCESSION NUMBER:		0001240147-04-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040421
FILED AS OF DATE:		20040422

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MESA LABORATORIES INC /CO
		CENTRAL INDEX KEY:			0000724004
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL INSTRUMENTS FOR MEASUREMENT, DISPLAY, AND CONTROL [3823]
		IRS NUMBER:				840872291
		STATE OF INCORPORATION:			CO
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		12100 W 6TH AVE
		CITY:			LAKEWOOD
		STATE:			CO
		ZIP:			80228
		BUSINESS PHONE:		3039878000

	MAIL ADDRESS:	
		STREET 1:		12100 W 6TH AVE
		CITY:			LUKEWOOD
		STATE:			CO
		ZIP:			80228

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MESA MEDICAL INC
		DATE OF NAME CHANGE:	19921123

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DUKE PAUL D
		CENTRAL INDEX KEY:			0001240147

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-11740
		FILM NUMBER:		04747634

	BUSINESS ADDRESS:	
		STREET 1:		12100 W 6TH AVENUE
		CITY:			LAKEWOOD
		STATE:			CO
		ZIP:			80228
		BUSINESS PHONE:		3039878000

	MAIL ADDRESS:	
		STREET 1:		12100 W 6TH AVENUE
		CITY:			LAKEWOOD
		STATE:			CO
		ZIP:			80228
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-04-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000724004</issuerCik>
        <issuerName>MESA LABORATORIES INC /CO</issuerName>
        <issuerTradingSymbol>MLAB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001240147</rptOwnerCik>
            <rptOwnerName>DUKE PAUL D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>12100 W 6TH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LAKEWOOD</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80228</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>2004-04-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.9</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>96466</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>/s/Paul D Duke by Luke Schmieder, attorney-in-fact</signatureName>
        <signatureDate>2004-04-22</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----