-----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,
 AY2ZoaThT97ss14qOfPLugo/9qztxrcuMEBodZWY6uzOu5V/dsubkV6VZ5rYAUhq
 Ox+fq8azOUeFyAhSmQXhGQ==

<SEC-DOCUMENT>0001054290-05-000001.txt : 20050505
<SEC-HEADER>0001054290-05-000001.hdr.sgml : 20050505
<ACCEPTANCE-DATETIME>20050505161103
ACCESSION NUMBER:		0001054290-05-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050504
FILED AS OF DATE:		20050505
DATE AS OF CHANGE:		20050505

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			US LEC CORP
		CENTRAL INDEX KEY:			0001054290
		STANDARD INDUSTRIAL CLASSIFICATION:	TELEPHONE COMMUNICATIONS (NO RADIO TELEPHONE) [4813]
		IRS NUMBER:				562065535
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		6801 MORRISON BOULEVARD
		STREET 2:		MORROCROFT III
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28211
		BUSINESS PHONE:		704-319-1000

	MAIL ADDRESS:	
		STREET 1:		6801 MORRISON BOULEVARD
		STREET 2:		MORROCROFT III
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28211

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			AAB RICHARD T
		CENTRAL INDEX KEY:			0001060471

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24061
		FILM NUMBER:		05803813

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		7043196040

	MAIL ADDRESS:	
		STREET 1:		212 SOUTH TRYON STREET
		STREET 2:		SUITE 1540
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28281
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-05-04</periodOfReport>

    <issuer>
        <issuerCik>0001054290</issuerCik>
        <issuerName>US LEC CORP</issuerName>
        <issuerTradingSymbol>CLEC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001060471</rptOwnerCik>
            <rptOwnerName>AAB RICHARD T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>6801 MORRISON BOULEVARD</rptOwnerStreet1>
            <rptOwnerStreet2>MORROCROFT III</rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28211</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-05-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>15000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5311456</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-05-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.19</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5316456</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4309500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Melrich Associates LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Richard T. Aab</signatureName>
        <signatureDate>2005-05-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----