AMENDMENT NO. 6 TO THE AMENDED AND RESTATED STOCKHOLDERS AGREEMENT AMENDMENT NO. 6 dated as of June 1, 1999 to the Amended and Restated Stockholders Agreement, dated as of October 31, 1997 (as heretofore amended, the "Stockholders Agreement") among KMC Telecom Holdings, Inc., Nassau Capital Partners L.P., NAS Partners I L.L.C., Harold N. Kamine, Newcourt Commercial Finance Corporation (as successor to AT&T Credit Corporation), General Electric Capital Corporation, First Union National Bank (as successor to CoreStates Bank, N.A.), KMC Telecommunications L.P., and CoreStates Holdings, Inc. W I T N E S S E T H WHEREAS, the parties hereto desire to make certain amendments to the Stockholders Agreement; NOW, THEREFORE, in consideration of the premises and for other good and valuable consideration the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree as follows: 1. DEFINED TERMS; AMENDMENTS TO SECTION 1 OF THE STOCKHOLDERS AGREEMENT. Unless otherwise defined herein, all capitalized terms defined in the Stockholders Agreement and used herein are so used as so defined. In addition, Section 1 of the Stockholders Agreement is amended by replacing the existing definitions with those set forth below. "PREFERRED STOCK REGISTRATION RIGHTS AGREEMENT" means the Preferred Stock Registration Rights Agreement dated as of April 30, 1999 between the Company and First Union Investors, Inc., as amended by Amendment No. 1 dated as of the date hereof. "PREFERRED STOCK WARRANT AGREEMENT" means the Warrant Agreement dated as of February 4, 1999 among the Company, The Chase Manhattan Bank, as Warrant Agent, Newcourt Capital USA, Inc., Lucent Technologies Inc. and any Additional Purchasers (as defined therein), as amended by Amendment No. 1 dated as of April 30, 1999, and as further amended by Amendment No. 2 dated as of the date hereof. 2. AMENDMENTS TO SECTIONS 6.1 OF THE STOCKHOLDERS AGREEMENT. The last sentence of paragraph (g)(ii) of Section 6.1 of the Stockholders Agreement is amended to read as follows: 6.1 DEMAND REGISTRATIONS. (g) OTHER REGISTRATION RIGHTS. (ii) Notwithstanding the foregoing or anything to the contrary contained in this Agreement, the Company may grant registration rights to the holders of Series E Preferred Stock and Series F Preferred Stock pursuant to the Preferred Stock Registration Rights Agreement as provided therein. 3. Except as expressly amended hereby, all of the provisions of the Stockholders Agreement are hereby affirmed and shall continue in full force and effect in accordance with their terms. 4. This Amendment shall be governed and construed in accordance with the laws of the state of Delaware applicable to agreements made and to be performed entirely within such state, without regard to the principles of conflicts of laws thereof. 5. This Amendment may be executed in one or more counterparts, each of which shall be deemed an original and all of which, taken together, shall constitute one and the same instrument. IN WITNESS WHEREOF, the undersigned have executed, or caused to be executed, this Agreement as of the date first above written. KMC TELECOM HOLDINGS, INC. By:/s/ James D. Greenfell _______________________________ Name: James D. Greenfell Title: Chief Financial Officer NASSAU CAPITAL PARTNERS L.P. By: Nassau Capital L.L.C., its General Partner By: /s/ John G. Quigley _____________________________ Name: John G. Quigley Title: Member NAS PARTNERS I L.L.C. By: /s/ John G. Quigley _____________________________ Name: John G. Quigley Title: Member HAROLD N. KAMINE in his individual capacity /s/ Harold N. Kamine ____________________________________ Harold N. Kamine NEWCOURT COMMERCIAL FINANCE CORPORATION By:/s/ John P. Sirico ______________________________ Name: John P. Sirico, II Title: Vice President Signature Page to Amendment No. 6 to the Amended and Restated Stockholders Agreement FIRST UNION NATIONAL BANK By:/s/ Pearce Landry ____________________________ Name: Pearce A. Landry Title: Vice President CORESTATES HOLDINGS, INC. By:/s/ Tracey M. Chaffin _______________________________ Name: Tracey M. Chaffin Title: Vice President GENERAL ELECTRIC CAPITAL CORPORATION By:/s/ M. Mylon ________________________________ Name: Mark F. Mylon Title: Manager-Operating KMC TELECOMMUNICATIONS L.P. By:/s/ Gerard M. Russomagno ________________________________ Name: Gerard M. Russomagno Title: General Managing Partner Signature Page to Amendment No. 6 to the Amended and Restated Stockholders Agreement