<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-11-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000726517</issuerCik>
        <issuerName>MERCHANTS BANCSHARES INC</issuerName>
        <issuerTradingSymbol>e6mc$ahj</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001071287</rptOwnerCik>
            <rptOwnerName>DAVIS CHARLES A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 CAPE MAY ST</rptOwnerStreet1>
            <rptOwnerStreet2>1 CAPE MAY ST</rptOwnerStreet2>
            <rptOwnerCity>HARRISON</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>07029</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>2005-11-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>0</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25.3</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>279069</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <remarks>This Form 4/A is filed to amend the Form 4 filed on 11/11/2005. The 1015 shares inadvertently reported sold on 11/9/2005 in fact remained in the reporting person's name and were transferred to the reporting person's broker.</remarks>

    <ownerSignature>
        <signatureName>Lisa Razo</signatureName>
        <signatureDate>2006-02-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Charles A. Davis</signatureName>
        <signatureDate>2006-02-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
[{"type": "4", "sequence": "1", "filename": "primary_doc.xml", "description": "PRIMARY DOCUMENT", "secsgml_size_bytes": 3334}]
X0202
4
2005-11-09
0
0000726517
MERCHANTS BANCSHARES INC
e6mc$ahj
0001071287
DAVIS CHARLES A
1 CAPE MAY ST
1 CAPE MAY ST
HARRISON
NJ
07029
1
0
0
0
Common Stock
2005-11-09
4
S
0
0
25.3
A
279069
D
This Form 4/A is filed to amend the Form 4 filed on 11/11/2005. The 1015 shares inadvertently reported sold on 11/9/2005 in fact remained in the reporting person's name and were transferred to the reporting person's broker.
Lisa Razo
2006-02-14
Charles A. Davis
2006-02-14