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.


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          (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.


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                  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


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                                 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