-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 OWOgKf1O6h8UkSno+WUGnmdl1iN3z5NjP6Z/Qaw1CSpFNm8h/bcvEH9Zn5hMvZPr
 Aa8WSJFjqHX3txM8XS+MlA==

<SEC-DOCUMENT>0001251010-04-000001.txt : 20040820
<SEC-HEADER>0001251010-04-000001.hdr.sgml : 20040820
<ACCEPTANCE-DATETIME>20040820112911
ACCESSION NUMBER:		0001251010-04-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	19951228
FILED AS OF DATE:		20040820

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DUFFY PATRICK G
		CENTRAL INDEX KEY:			0001251010

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-17000
		FILM NUMBER:		04987974

	BUSINESS ADDRESS:	
		STREET 1:		731 N STATE STREET
		CITY:			ALMA
		STATE:			MI
		ZIP:			48847
		BUSINESS PHONE:		9894634921

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COMMERCIAL NATIONAL FINANCIAL CORP /MI
		CENTRAL INDEX KEY:			0000828535
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				382799780
		STATE OF INCORPORATION:			MI
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		101 N PINE RIVER ST
		CITY:			ITHACA
		STATE:			MI
		ZIP:			48847
		BUSINESS PHONE:		5178754144

	MAIL ADDRESS:	
		STREET 1:		P O BOX 280
		CITY:			ITHACA
		STATE:			MI
		ZIP:			48847
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>1995-12-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000828535</issuerCik>
        <issuerName>COMMERCIAL NATIONAL FINANCIAL CORP /MI</issuerName>
        <issuerTradingSymbol>cefc</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001251010</rptOwnerCik>
            <rptOwnerName>DUFFY PATRICK G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Vice President &amp; CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-08-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1700</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>6.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9171.063</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>6.5</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-08-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1700</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>6.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>1997-12-01</value>
            </exerciseDate>
            <expirationDate>
                <value>2007-06-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1700</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1461</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <ownerSignature>
        <signatureName>Patrick G. Duffy</signatureName>
        <signatureDate>2004-08-20</signatureDate>
    </ownerSignature>
</ownershipDocument>

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