As filed with the Securities and Exchange Commission on December 11, 2003
                                                           Registration No. 333-
--------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                           ---------------------------
                         FORM S-8 REGISTRATION STATEMENT
                        UNDER THE SECURITIES ACT OF 1933
                           ---------------------------
                           MPOWER HOLDING CORPORATION
             (Exact name of registrant as specified in its charter)


         Delaware                                          52-2232143
(State or other jurisdiction of                          (I.R.S. Employer
incorporation or organization)                          Identification No.)


                          175 Sully's Trail, Suite 300
                            Pittsford, New York 14534
                                 (585) 218-6550

  (Address and phone number of principal executive offices, including zip code)
                           ---------------------------
                 MPOWER HOLDING CORPORATION STOCK OPTION PLAN I

                            (Full title of the plans)

                           Russell I. Zuckerman, Esq.
                     Senior Vice President, General Counsel
                             and Corporate Secretary
                          175 Sully's Trail, Suite 300
                            Pittsford, New York 14534
                                 (585) 218-6550

            (Name, address and telephone number of agent for service)

                           ---------------------------

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------------------------------------------
  Title of securities          Amount to be           Proposed maximum          Proposed maximum             Amount of
    to be registered          registered (1)         offering price per     aggregate offering price     registration fee
                                                            share
--------------------------------------------------------------------------------------------------------------------------
<S>                              <C>                    <C>                        <C>                       <C>
Common Stock, par value          2,000,000              $1.32 (2)                  $2,640,000                $213.58
$.001 per share


--------------------------------------------------------------------------------------------------------------------------
</TABLE>

(1)      This registration statement on Form S-8 (this "Registration Statement")
         represents an aggregate of 2,000,000 shares of Common Stock, par value
         $.001 per share (the "Common Stock") of Mpower Holding Corporation (the
         "Registrant") available for issuance under the Mpower Holding
         Corporation Option Plan I. In addition, this Registration Statement
         shall also cover any additional shares of Common Stock that become
         issuable under the plan being registered pursuant to this Registration
         Statement by reason of any stock dividend, stock split,
         recapitalization or any other similar transaction effected without the
         receipt of consideration which results in an increase in the number of
         the Registrant's outstanding shares of Common Stock.

(2)      Pursuant to Rules 457(c) and 457(h) of the Securities Act of 1933, as
         amended (the "Securities Act"), the Proposed Maximum Offering Price Per
         Share and the Proposed Maximum Aggregate Offering Price for 2,000,000
         shares of Common Stock under Mpower Holding Corporation Option Plan I
         have been estimated solely for the purpose of calculating the
         registration fee and are based on the average of the high and low sales
         prices of the Common Stock on the NASD Over-the-Counter Bulletin Board
         on December 10, 2003.

<PAGE>


                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information.*

Item 2.  Registrant Information and Employee Plan Annual Information.*









____________

*        Information required by Part I to be contained in the Section 10(a)
         prospectus is omitted from this Registration Statement in accordance
         with Rule 428 under the Securities Act and the "Note" to Part I of Form
         S-8.

<PAGE>


                                     PART II


               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


Item 3.   Incorporation of Documents by Reference.

          The following documents, which have been filed with or furnished to
the Securities and Exchange Commission (the "Commission") by the Registrant, are
incorporated herein by reference and made part of this Registration Statement:

               (a) the Registrant's Annual Report on Form 10-K for fiscal year
          ended December 31, 2002, filed with the Commission on March 28, 2003;

               (b) the Registrant's Quarterly Reports on Form 10-Q for the
          quarterly periods ended March 31, 2003, filed with the Commission on
          May 14, 2003, June 30, 2003, filed with the Commission on August 12,
          2003 and September 30, 2003, filed with the Commission on November 13,
          2003;

               (c) the Registrant's Current Reports on Form 8-K filed with the
          Commission on January 17, 2003, March 17, 2003, March 28, 2003, April
          22, 2003, May 8, 2003, July 16, 2003, August 6, 2003, September 30,
          2003 and November 6, 2003; and

               (d) description of the Registrant's Common Stock as set forth in
          the Registrant's Registration Statement on Form 8-A, filed with the
          Commission on July 30, 2002.

          In addition, all documents filed by the Registrant pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), subsequent to the effective date of this
Registration Statement and prior to the filing of a post-effective amendment to
this Registration Statement indicating that all securities offered hereby have
been sold or deregistering all securities then remaining unsold, shall be deemed
to be incorporated by reference herein and to be a part hereof from the date of
filing of such documents. Any statement contained herein or in any document
incorporated or deemed to be incorporated by reference herein shall be deemed to
be modified or superseded for purposes of this Registration Statement to the
extent that a statement contained herein or in any other subsequently filed
document which also is or is deemed to be incorporated by reference herein
modifies or supersedes such statement. Any such statement so modified or
superseded shall not be deemed to constitute a part of this Registration
Statement, except as so modified or superseded.

Item 4.   Description of Securities.

          Not Applicable.

Item 5.   Interests of Named Experts and Counsel.

               Not Applicable.

Item 6.   Indemnification of Directors and Officers.

          The certificate of incorporation and the by-laws of the Registrant
state that the Registrant shall indemnify any officer or director in the event
he is made a party to a proceeding or is threatened to be made a party to any
threatened, pending, or completed action, suit or proceeding, whether criminal,
administrative or investigative (other than an action by or on behalf of the
Registrant), because he is or was a director or officer against expenses
(including attorneys' fees), judgments, fines, and amounts paid in settlement
actually and reasonably incurred by the

<PAGE>


officer or director in such action, suit or proceeding if he acted in good faith
and in a manner he reasonably believed to be in or not opposed to the best
interests of the Registrant and, in regard to any criminal proceeding, he had no
reasonable cause to believe his conduct was unlawful. The Registrant's
certificate of incorporation and by-laws further state that the Registrant shall
not indemnify any officer or director in connection with a proceeding in which
such officer or director was adjudged liable to the Registrant, unless and only
to the extent the court in which the proceeding was brought upon application
determines that despite the adjudication of liability and in view of all of the
circumstances of the case, the officer or director is fairly and reasonably
entitled to indemnity for such expenses as the court deems proper.

          The certificate of incorporation and by-laws provide that, to the
extent that a present or former director or officer has been successful on the
merits or otherwise in defense of any action, suit or proceeding, or in defense
of any claim, issue or matter therein, he shall be indemnified against expenses
(including attorneys' fees) actually and reasonably incurred by him in
connection therewith. The Registrant's certificate of incorporation and by-laws
further provide that the Registrant shall not indemnify any officer or director
unless a separate determination has been made that indemnification of such
officer or director is permissible because he has met the standard of conduct
set forth in the Registrant's certificate or incorporation or by-laws,
respectively.

          The determination required to be made by the Registrant's certificate
of incorporation and by-laws shall be made, with regard to a person who is a
director or officer at the time of the determination:

          1.   by the board of directors of the Registrant by majority vote of
               directors not at the time parties to the proceeding, even if less
               than a quorum;

          2.   by a committee of disinterested directors designated by a
               majority vote of the disinterested directors, even if less than a
               quorum;

          3.   if there are no such directors or if such directors so direct, by
               independent legal counsel in a written opinion; or

          4.   by the shareholders of the Registrant.

          The Registrant's certificate of incorporation and by-laws further
provide that the Registrant may pay for or reimburse the reasonable expenses
incurred by an officer or director as a party to a proceeding in advance of
final disposition of the proceeding if the officer or director furnishes to the
Registrant a written undertaking to repay any advances if it is ultimately
determined that he is not entitled to any indemnification under the Registrant's
certificate of incorporation or by-laws, respectively.

          The Registrant's certificate of incorporation and by-laws also provide
that the rights of an officer or director to indemnification set forth in the
Registrant's certificate of incorporation or by-laws, respectively, shall be in
addition to any other rights with respect to indemnification, advancement of
expenses or otherwise that such officer or director may be entitled to under
law, by-law, agreement, vote of stockholders or disinterested directors or
otherwise, both as to action in such person's official capacity and as to action
in another capacity while holding such office.

          The Registrant's certificate of incorporation provides that it is the
intention of the Registrant to provide the indemnification of officers and
directors only to the maximum amount permissible under Delaware law.

          With certain limitations, Section 145(a) of the General Corporation
Law of the State of Delaware (the "DGCL") permits a corporation to indemnify a
director or officer who is a party or is threatened to be made a party to any
threatened, pending or completed action, suit or proceeding, whether civil,
criminal, administrative or investigative, by reason of the fact that he is or
was a director, officer, employee or agent of the corporation, or is or was
serving at the request of the corporation as a director, officer, employee or
agent of another corporation, partnership, joint venture, trust or other
enterprise, against expenses, including attorneys fees, judgments, fines and
amounts paid in settlement actually and reasonably incurred by him in connection
with the action, suit or proceeding if he acted in good faith and in a manner
which he reasonably believed to be in or not opposed to the interest of the

<PAGE>


corporation, and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his conduct was unlawful.

          As permitted by Section 145(g) of the DGCL, the Registrant maintains
liability insurance covering directors and officers.

          The Registrant has also entered into indemnification agreements with
each of its directors and executive officers. Under the terms of the
indemnification agreements, the Registrant has agreed to indemnify the directors
and executive officers from and against any expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement incurred by the directors
and executive officers by reason of being made a party or threatened to be made
a party to any threatened, pending or completed action suit or proceeding by
reason of any act or omission to act during such officer's or director's term as
such or otherwise by reason of the fact that such person is or was a director or
officer of the Registrant or any subsidiary or affiliate of the Registrant, to
the fullest extent permitted by the DGCL.

          The indemnification agreements obligate the Registrant to maintain a
directors and officer's insurance policy, including a "tail policy" that
provides coverage for six years following the date that the individual ceases to
be an director or executive officer. The Registrant is also obligated to
maintain a trust to provide for the payment of the premiums under the "tail
policy." The agreements further provide that no indemnity will be paid to the
extent that the expenses arise from an executive officer's or director's
violation of law, violation of Section 16(b) of the Exchange Act or conduct that
is finally adjudged to have been knowingly fraudulent, deliberately dishonest or
willful misconduct.

Item 7.   Exemption from Registration Claimed.

          Not Applicable.

Item 8.   Exhibits.

          See Exhibit Index.


Item 9.   Undertakings.

          (a)  The undersigned Registrant hereby undertakes:

               (1)   To file, during any period in which offers or sales are
          being made, a post-effective amendment to this Registration Statement:

               (i)   to include any prospectus required by Section 10(a)(3) of
                     the Securities Act;

               (ii)  to reflect in the prospectus any facts or events arising
                     after the effective date of this Registration Statement (or
                     the most recent post-effective amendment thereof) which,
                     individually or in the aggregate, represent a fundamental
                     change in the information set forth in the Registration
                     Statement;

               (iii) any material information with respect to the plan of
                     distribution not previously disclosed in this Registration
                     Statement or any material change to such information in the
                     Registration Statement;

               (2)   That, for the purpose of determining any liability under
          the Securities Act, each such post-effective amendment shall be deemed
          to be a new registration statement relating to the securities offered
          therein, and the offering of such securities at that time shall be
          deemed to be the initial bona fide offering thereof; and

<PAGE>


               (3)   To remove from registration by means of a post-effective
          amendment any of the securities being registered which remain unsold
          at the termination of the offering.

          (b) The undersigned Registrant hereby undertakes that, for purposes of
determining liability under the Securities Act, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act
that is incorporated by reference in this Registration Statement shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof.

          (c) Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the Registrant pursuant to the foregoing provisions, or otherwise, the
Registrant has been advised that in the opinion of the Commission such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer, or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

<PAGE>


                                   SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8 and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the Town of Pittsford, State of New York, on this 11th day
of December, 2003.

                                 MPOWER HOLDING CORPORATION

                                 By: /s/ Rolla P. Huff
                                     -------------------------------------------
                                     Rolla P. Huff
                                     Chief Executive Officer and Chairman of the
                                     Board of Directors

<PAGE>


                                POWER OF ATTORNEY

          KNOW ALL MEN BY THESE PRESENTS that each person whose signature to
this Registration Statement appears below hereby constitutes and appoints each
of Rolla P. Huff, S. Gregory Clevenger and Russell I. Zuckerman as such person's
true and lawful attorney-in-fact and agent, with full power of substitution and
resubstitution, for such person and in such person's name, place and stead, in
any and all capacities, to sign any and all amendments to the Registration
Statement, including post-effective amendments, and registrations statements
filed pursuant to Rule 462 under the Securities Act, and to file the same, with
all exhibits thereto, and other documents in connection therewith, with the
Commission, and does hereby grant unto each said attorney-in-fact and agent full
power and authority to do and perform each and every act and thing requisite and
necessary to be done in and about the premises, as fully to all intents and
purposes as such person might or could do in person, hereby ratifying and
confirming all that each said attorney-in-fact and agent, or any substitute
therefor, may lawfully do or cause to be done by virtue hereof.

          Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on the 11th day of December, 2003.

         SIGNATURE                                    TITLE
         ---------                                    -----

/s/ Rolla P. Huff
--------------------------                    Chief Executive Officer and
Rolla P. Huff                                 Chairman of the Board of Directors

/s/ Robert M. Pomeroy
--------------------------                    Director
Robert M. Pomeroy

/s/ Michael E. Cahr
--------------------------                    Director
Michael E. Cahr

/s/ Anthony J. Cassara
--------------------------                    Director
Anthony J. Cassara

/s/ Richard L. Shorten, Jr.
--------------------------                    Director
Richard L. Shorten, Jr.

/s/ Michael M. Earley
--------------------------                    Director
Michael M. Earley

/s/ S. Gregory Clevenger
--------------------------                    Executive Vice President, Chief
S. Gregory Clevenger                          Financial Officer (Principal
                                              Financial Officer)
/s/ Michael J. Tschiderer
--------------------------                    Vice President of Finance,
Michael J. Tschiderer                         Controller and Treasurer
                                              (Principal Accounting Officer)
/s/ Russell I. Zuckerman
--------------------------                    Senior Vice President, General
Russell I. Zuckerman                          Counsel and Corporate Secretary

<PAGE>


                                  Exhibit Index

Exhibit No.       Description of Document

3.1               Second Amended and Restated Certificate of Incorporation of
                  Mpower Registrant Corporation, (incorporated by reference to
                  Exhibit 3.1 to the Registrant's Registration Statement on Form
                  8-A filed with the Commission on July 30, 2002).

3.2               Amended and Restated By-laws of Mpower Registrant Corporation
                  (incorporated by reference to Exhibit 3.2 to the Registrant's
                  Registration Statement on Form 8-A filed with the Commission
                  on July 30, 2002).

4.1               Mpower Holding Corporation Stock Option Plan I (incorporated
                  by reference to Exhibit 4.1 to the Registrant's Registration
                  Statement on Form S-8 filed with the Commission on June 19,
                  2003).

*5.1              Opinion of Russell I. Zuckerman, Senior Vice President,
                  General Counsel and Corporate Secretary of Registrant as to
                  the legality of the securities being registered.

*23.1             Consent of Russell I. Zuckerman, Senior Vice President,
                  General Counsel and Corporate Secretary of Registrant
                  (contained in opinion filed as Exhibit 5.1).

*23.2             Consent of Deloitte & Touche LLP.

*24               Powers of Attorney (contained in the signature page of
                  Registration Statement).

__________________
*  Filed herewith
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As filed with the Securities and Exchange Commission on December 11, 2003
                                                           Registration No. 333-
--------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                           ---------------------------
                         FORM S-8 REGISTRATION STATEMENT
                        UNDER THE SECURITIES ACT OF 1933
                           ---------------------------
                           MPOWER HOLDING CORPORATION
             (Exact name of registrant as specified in its charter)

         Delaware                                          52-2232143
(State or other jurisdiction of                          (I.R.S. Employer
incorporation or organization)                          Identification No.)

                          175 Sully's Trail, Suite 300
                            Pittsford, New York 14534
                                 (585) 218-6550

  (Address and phone number of principal executive offices, including zip code)
                           ---------------------------
                 MPOWER HOLDING CORPORATION STOCK OPTION PLAN I

                            (Full title of the plans)

                           Russell I. Zuckerman, Esq.
                     Senior Vice President, General Counsel
                             and Corporate Secretary
                          175 Sully's Trail, Suite 300
                            Pittsford, New York 14534
                                 (585) 218-6550

            (Name, address and telephone number of agent for service)

                           ---------------------------
--------------------------------------------------------------------------------------------------------------------------
  Title of securities          Amount to be           Proposed maximum          Proposed maximum             Amount of
    to be registered          registered (1)         offering price per     aggregate offering price     registration fee
                                                            share
--------------------------------------------------------------------------------------------------------------------------
Common Stock, par value          2,000,000              $1.32 (2)                  $2,640,000                $213.58
$.001 per share

--------------------------------------------------------------------------------------------------------------------------
(1)      This registration statement on Form S-8 (this "Registration Statement")
         represents an aggregate of 2,000,000 shares of Common Stock, par value
         $.001 per share (the "Common Stock") of Mpower Holding Corporation (the
         "Registrant") available for issuance under the Mpower Holding
         Corporation Option Plan I. In addition, this Registration Statement
         shall also cover any additional shares of Common Stock that become
         issuable under the plan being registered pursuant to this Registration
         Statement by reason of any stock dividend, stock split,
         recapitalization or any other similar transaction effected without the
         receipt of consideration which results in an increase in the number of
         the Registrant's outstanding shares of Common Stock.

(2)      Pursuant to Rules 457(c) and 457(h) of the Securities Act of 1933, as
         amended (the "Securities Act"), the Proposed Maximum Offering Price Per
         Share and the Proposed Maximum Aggregate Offering Price for 2,000,000
         shares of Common Stock under Mpower Holding Corporation Option Plan I
         have been estimated solely for the purpose of calculating the
         registration fee and are based on the average of the high and low sales
         prices of the Common Stock on the NASD Over-the-Counter Bulletin Board
         on December 10, 2003.
PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information.*

Item 2.  Registrant Information and Employee Plan Annual Information.*

____________

*        Information required by Part I to be contained in the Section 10(a)
         prospectus is omitted from this Registration Statement in accordance
         with Rule 428 under the Securities Act and the "Note" to Part I of Form
         S-8.
PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.   Incorporation of Documents by Reference.

          The following documents, which have been filed with or furnished to
the Securities and Exchange Commission (the "Commission") by the Registrant, are
incorporated herein by reference and made part of this Registration Statement:

               (a) the Registrant's Annual Report on Form 10-K for fiscal year
          ended December 31, 2002, filed with the Commission on March 28, 2003;

               (b) the Registrant's Quarterly Reports on Form 10-Q for the
          quarterly periods ended March 31, 2003, filed with the Commission on
          May 14, 2003, June 30, 2003, filed with the Commission on August 12,
          2003 and September 30, 2003, filed with the Commission on November 13,
          2003;

               (c) the Registrant's Current Reports on Form 8-K filed with the
          Commission on January 17, 2003, March 17, 2003, March 28, 2003, April
          22, 2003, May 8, 2003, July 16, 2003, August 6, 2003, September 30,
          2003 and November 6, 2003; and

               (d) description of the Registrant's Common Stock as set forth in
          the Registrant's Registration Statement on Form 8-A, filed with the
          Commission on July 30, 2002.

          In addition, all documents filed by the Registrant pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), subsequent to the effective date of this
Registration Statement and prior to the filing of a post-effective amendment to
this Registration Statement indicating that all securities offered hereby have
been sold or deregistering all securities then remaining unsold, shall be deemed
to be incorporated by reference herein and to be a part hereof from the date of
filing of such documents. Any statement contained herein or in any document
incorporated or deemed to be incorporated by reference herein shall be deemed to
be modified or superseded for purposes of this Registration Statement to the
extent that a statement contained herein or in any other subsequently filed
document which also is or is deemed to be incorporated by reference herein
modifies or supersedes such statement. Any such statement so modified or
superseded shall not be deemed to constitute a part of this Registration
Statement, except as so modified or superseded.

Item 4.   Description of Securities.

          Not Applicable.

Item 5.   Interests of Named Experts and Counsel.

               Not Applicable.

Item 6.   Indemnification of Directors and Officers.

          The certificate of incorporation and the by-laws of the Registrant
state that the Registrant shall indemnify any officer or director in the event
he is made a party to a proceeding or is threatened to be made a party to any
threatened, pending, or completed action, suit or proceeding, whether criminal,
administrative or investigative (other than an action by or on behalf of the
Registrant), because he is or was a director or officer against expenses
(including attorneys' fees), judgments, fines, and amounts paid in settlement
actually and reasonably incurred by the
officer or director in such action, suit or proceeding if he acted in good faith
and in a manner he reasonably believed to be in or not opposed to the best
interests of the Registrant and, in regard to any criminal proceeding, he had no
reasonable cause to believe his conduct was unlawful. The Registrant's
certificate of incorporation and by-laws further state that the Registrant shall
not indemnify any officer or director in connection with a proceeding in which
such officer or director was adjudged liable to the Registrant, unless and only
to the extent the court in which the proceeding was brought upon application
determines that despite the adjudication of liability and in view of all of the
circumstances of the case, the officer or director is fairly and reasonably
entitled to indemnity for such expenses as the court deems proper.

          The certificate of incorporation and by-laws provide that, to the
extent that a present or former director or officer has been successful on the
merits or otherwise in defense of any action, suit or proceeding, or in defense
of any claim, issue or matter therein, he shall be indemnified against expenses
(including attorneys' fees) actually and reasonably incurred by him in
connection therewith. The Registrant's certificate of incorporation and by-laws
further provide that the Registrant shall not indemnify any officer or director
unless a separate determination has been made that indemnification of such
officer or director is permissible because he has met the standard of conduct
set forth in the Registrant's certificate or incorporation or by-laws,
respectively.

          The determination required to be made by the Registrant's certificate
of incorporation and by-laws shall be made, with regard to a person who is a
director or officer at the time of the determination:

          1.   by the board of directors of the Registrant by majority vote of
               directors not at the time parties to the proceeding, even if less
               than a quorum;

          2.   by a committee of disinterested directors designated by a
               majority vote of the disinterested directors, even if less than a
               quorum;

          3.   if there are no such directors or if such directors so direct, by
               independent legal counsel in a written opinion; or

          4.   by the shareholders of the Registrant.

          The Registrant's certificate of incorporation and by-laws further
provide that the Registrant may pay for or reimburse the reasonable expenses
incurred by an officer or director as a party to a proceeding in advance of
final disposition of the proceeding if the officer or director furnishes to the
Registrant a written undertaking to repay any advances if it is ultimately
determined that he is not entitled to any indemnification under the Registrant's
certificate of incorporation or by-laws, respectively.

          The Registrant's certificate of incorporation and by-laws also provide
that the rights of an officer or director to indemnification set forth in the
Registrant's certificate of incorporation or by-laws, respectively, shall be in
addition to any other rights with respect to indemnification, advancement of
expenses or otherwise that such officer or director may be entitled to under
law, by-law, agreement, vote of stockholders or disinterested directors or
otherwise, both as to action in such person's official capacity and as to action
in another capacity while holding such office.

          The Registrant's certificate of incorporation provides that it is the
intention of the Registrant to provide the indemnification of officers and
directors only to the maximum amount permissible under Delaware law.

          With certain limitations, Section 145(a) of the General Corporation
Law of the State of Delaware (the "DGCL") permits a corporation to indemnify a
director or officer who is a party or is threatened to be made a party to any
threatened, pending or completed action, suit or proceeding, whether civil,
criminal, administrative or investigative, by reason of the fact that he is or
was a director, officer, employee or agent of the corporation, or is or was
serving at the request of the corporation as a director, officer, employee or
agent of another corporation, partnership, joint venture, trust or other
enterprise, against expenses, including attorneys fees, judgments, fines and
amounts paid in settlement actually and reasonably incurred by him in connection
with the action, suit or proceeding if he acted in good faith and in a manner
which he reasonably believed to be in or not opposed to the interest of the
corporation, and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his conduct was unlawful.

          As permitted by Section 145(g) of the DGCL, the Registrant maintains
liability insurance covering directors and officers.

          The Registrant has also entered into indemnification agreements with
each of its directors and executive officers. Under the terms of the
indemnification agreements, the Registrant has agreed to indemnify the directors
and executive officers from and against any expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement incurred by the directors
and executive officers by reason of being made a party or threatened to be made
a party to any threatened, pending or completed action suit or proceeding by
reason of any act or omission to act during such officer's or director's term as
such or otherwise by reason of the fact that such person is or was a director or
officer of the Registrant or any subsidiary or affiliate of the Registrant, to
the fullest extent permitted by the DGCL.

          The indemnification agreements obligate the Registrant to maintain a
directors and officer's insurance policy, including a "tail policy" that
provides coverage for six years following the date that the individual ceases to
be an director or executive officer. The Registrant is also obligated to
maintain a trust to provide for the payment of the premiums under the "tail
policy." The agreements further provide that no indemnity will be paid to the
extent that the expenses arise from an executive officer's or director's
violation of law, violation of Section 16(b) of the Exchange Act or conduct that
is finally adjudged to have been knowingly fraudulent, deliberately dishonest or
willful misconduct.

Item 7.   Exemption from Registration Claimed.

          Not Applicable.

Item 8.   Exhibits.

          See Exhibit Index.

Item 9.   Undertakings.

          (a)  The undersigned Registrant hereby undertakes:

               (1)   To file, during any period in which offers or sales are
          being made, a post-effective amendment to this Registration Statement:

               (i)   to include any prospectus required by Section 10(a)(3) of
                     the Securities Act;

               (ii)  to reflect in the prospectus any facts or events arising
                     after the effective date of this Registration Statement (or
                     the most recent post-effective amendment thereof) which,
                     individually or in the aggregate, represent a fundamental
                     change in the information set forth in the Registration
                     Statement;

               (iii) any material information with respect to the plan of
                     distribution not previously disclosed in this Registration
                     Statement or any material change to such information in the
                     Registration Statement;

               (2)   That, for the purpose of determining any liability under
          the Securities Act, each such post-effective amendment shall be deemed
          to be a new registration statement relating to the securities offered
          therein, and the offering of such securities at that time shall be
          deemed to be the initial bona fide offering thereof; and
(3)   To remove from registration by means of a post-effective
          amendment any of the securities being registered which remain unsold
          at the termination of the offering.

          (b) The undersigned Registrant hereby undertakes that, for purposes of
determining liability under the Securities Act, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act
that is incorporated by reference in this Registration Statement shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof.

          (c) Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the Registrant pursuant to the foregoing provisions, or otherwise, the
Registrant has been advised that in the opinion of the Commission such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer, or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.
SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8 and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the Town of Pittsford, State of New York, on this 11th day
of December, 2003.

                                 MPOWER HOLDING CORPORATION

                                 By: /s/ Rolla P. Huff
                                     -------------------------------------------
                                     Rolla P. Huff
                                     Chief Executive Officer and Chairman of the
                                     Board of Directors
POWER OF ATTORNEY

          KNOW ALL MEN BY THESE PRESENTS that each person whose signature to
this Registration Statement appears below hereby constitutes and appoints each
of Rolla P. Huff, S. Gregory Clevenger and Russell I. Zuckerman as such person's
true and lawful attorney-in-fact and agent, with full power of substitution and
resubstitution, for such person and in such person's name, place and stead, in
any and all capacities, to sign any and all amendments to the Registration
Statement, including post-effective amendments, and registrations statements
filed pursuant to Rule 462 under the Securities Act, and to file the same, with
all exhibits thereto, and other documents in connection therewith, with the
Commission, and does hereby grant unto each said attorney-in-fact and agent full
power and authority to do and perform each and every act and thing requisite and
necessary to be done in and about the premises, as fully to all intents and
purposes as such person might or could do in person, hereby ratifying and
confirming all that each said attorney-in-fact and agent, or any substitute
therefor, may lawfully do or cause to be done by virtue hereof.

          Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on the 11th day of December, 2003.

         SIGNATURE                                    TITLE
         ---------                                    -----

/s/ Rolla P. Huff
--------------------------                    Chief Executive Officer and
Rolla P. Huff                                 Chairman of the Board of Directors

/s/ Robert M. Pomeroy
--------------------------                    Director
Robert M. Pomeroy

/s/ Michael E. Cahr
--------------------------                    Director
Michael E. Cahr

/s/ Anthony J. Cassara
--------------------------                    Director
Anthony J. Cassara

/s/ Richard L. Shorten, Jr.
--------------------------                    Director
Richard L. Shorten, Jr.

/s/ Michael M. Earley
--------------------------                    Director
Michael M. Earley

/s/ S. Gregory Clevenger
--------------------------                    Executive Vice President, Chief
S. Gregory Clevenger                          Financial Officer (Principal
                                              Financial Officer)
/s/ Michael J. Tschiderer
--------------------------                    Vice President of Finance,
Michael J. Tschiderer                         Controller and Treasurer
                                              (Principal Accounting Officer)
/s/ Russell I. Zuckerman
--------------------------                    Senior Vice President, General
Russell I. Zuckerman                          Counsel and Corporate Secretary
Exhibit Index

Exhibit No.       Description of Document

3.1               Second Amended and Restated Certificate of Incorporation of
                  Mpower Registrant Corporation, (incorporated by reference to
                  Exhibit 3.1 to the Registrant's Registration Statement on Form
                  8-A filed with the Commission on July 30, 2002).

3.2               Amended and Restated By-laws of Mpower Registrant Corporation
                  (incorporated by reference to Exhibit 3.2 to the Registrant's
                  Registration Statement on Form 8-A filed with the Commission
                  on July 30, 2002).

4.1               Mpower Holding Corporation Stock Option Plan I (incorporated
                  by reference to Exhibit 4.1 to the Registrant's Registration
                  Statement on Form S-8 filed with the Commission on June 19,
                  2003).

*5.1              Opinion of Russell I. Zuckerman, Senior Vice President,
                  General Counsel and Corporate Secretary of Registrant as to
                  the legality of the securities being registered.

*23.1             Consent of Russell I. Zuckerman, Senior Vice President,
                  General Counsel and Corporate Secretary of Registrant
                  (contained in opinion filed as Exhibit 5.1).

*23.2             Consent of Deloitte & Touche LLP.

*24               Powers of Attorney (contained in the signature page of
                  Registration Statement).

__________________
*  Filed herewith