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                                                                    Exhibit 10.8

                                                                  EXECUTION COPY


                               AMENDMENT NO. 1 TO
                       NOTES REGISTRATION RIGHTS AGREEMENT

                  This AMENDMENT NO. 1 TO THE NOTES REGISTRATION RIGHTS
AGREEMENT, dated as of October 1, 2001 (this "AMENDMENT"), is made between
METROMEDIA FIBER NETWORK, INC., a Delaware corporation (the "COMPANY"), and
VERIZON INVESTMENTS INC., a Delaware corporation formerly known as Bell Atlantic
Investments, Inc. (the "PURCHASER"). Capitalized terms used herein that are not
defined herein shall have the meanings ascribed thereto in the Notes
Registration Rights Agreement (as defined below).

                                    RECITALS:

                  WHEREAS, as of October 7, 1999, the Company and the Purchaser
entered into that certain Securities Purchase Agreement (the "PURCHASE
AGREEMENT"), pursuant to which, among other things, the Company issued and sold
to the Purchaser shares of Class A common stock of the Company, par value $0.01
per share ("CLASS A COMMON STOCK"), and $975,281,000 principal amount of the
Company's 6.15% Convertible Subordinated Notes due 2010 (the "OLD CONVERTIBLE
NOTES"), which Convertible Notes are convertible into shares of Class A Common
Stock;

                  WHEREAS, in connection with the issuance and sale of the Class
A Common Stock and the Convertible Notes, the Company and the Purchaser entered
into that certain Notes Registration Rights Agreement, dated as of March 6, 2000
(as amended hereby, the "NOTES REGISTRATION RIGHTS AGREEMENT");

                  WHEREAS, the Company and the Purchaser executed that certain
Notes Purchase Agreement, dated as of October 1, 2001 (the "NEW PURCHASE
AGREEMENT"), pursuant to which, among other things, the Purchaser will purchase
from the Company one or more 8.5% Senior Secured Convertible Notes due 2011 in
the aggregate principal amount of $50,000,000 (the "NEW CONVERTIBLE NOTES"),
which shall be convertible into shares of Class A Common Stock pursuant to, and
in accordance with, the terms of the Indenture, dated as of October 1, 2001, by
and between the Company and Wilmington Trust Company, as trustee (the "NEW 8.5%
NOTES INDENTURE");

                  WHEREAS, the Company and the Purchaser executed that certain
Exchange Agreement, dated as of October 1, 2001, pursuant to which the Company
will exchange, and the Purchaser will surrender for exchange, the Old
Convertible Notes for $500,000,000 principal amount of the Company's 6.15%
Series A Convertible Subordinated Notes due March 16, 2010 and $475,281,000
principal amount of the Company's 6.15% Series B Convertible Subordinated Notes
due March 16, 2010, the terms of which shall be governed by an indenture, dated
as of October 1, 2001 (the "NEW 6.15% NOTES INDENTURE"), between the Company and
U.S. Bank Trust National Association, as trustee; and

                  WHEREAS, the Company and the Purchaser desire by this
Amendment to amend certain provisions of the Notes Registration Rights
Agreement.

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                  NOW, THEREFORE, it is hereby agreed as follows:

                  SECTION 1.        AMENDMENTS TO THE NOTES REGISTRATION RIGHTS
                                    AGREEMENT.

                  (a)      Section 1 of the Notes Registration Rights Agreement
is hereby amended by adding thereto the following new definitions in the
appropriate alphabetical location:

                           "NEW CONVERTIBLE NOTES" means one or more 8.5% senior
                  secured convertible notes due 2011 in the aggregate principal
                  amount of $50,000,000 issued pursuant to the New 8.5% Notes
                  Indenture.

                           "NEW 6.15% NOTES" means, collectively, the Series A
                  Convertible Notes and the Series B Convertible Notes.

                           "NEW 6.15% NOTES INDENTURE" means the indenture dated
                  as of October 1, 2001, by and between the Company and U.S.
                  Bank Trust National Association, as trustee, relating to the
                  New 6.15% Notes as such indenture may be amended, supplemented
                  or otherwise modified from time to time in accordance with the
                  terms thereof.

                           "NEW 8.5% NOTES INDENTURE" means the indenture, dated
                  as of October 1, 2001, by and between the Company and
                  Wilmington Trust Company, as trustee, relating to the New
                  Convertible Notes, as such Indenture may be amended,
                  supplemented or otherwise modified from time to time in
                  accordance with the terms thereof.

                           "PUBLIC RESALE" means a transfer of Registrable
                  Securities pursuant to (A) a bona fide secondary offering
                  registered under the Securities Act effectuated through the
                  exercise by the Purchaser or its permitted transferee of its
                  registration rights as contemplated by Section 2, 3 or 4 of
                  this Agreement, (B) a purchase agreement with a placement
                  agent or group of placement agents that contemplates the
                  immediate resale of securities by such placement agent or
                  group of placement agents, pursuant to the resale exemption
                  provided by Rule 144A, solely to QIBs and other permitted
                  purchasers under Rule 144A or in a transfer permitted by
                  Regulation S, or (C) bona fide "brokers transactions" as
                  permitted by the exemption from registration of the resale of
                  the shares of Class A Common Stock underlying the Convertible
                  Notes provided by Rule 144.

                           "QIB" means a "qualified institutional buyer" as
                  defined in Rule 144A.

                           "REGULATION S" means Regulation S promulgated under
                  the Securities Act.

                           "RULE 144A" means Rule 144A promulgated under the
                  Securities Act.


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                           "SERIES A CONVERTIBLE NOTES" shall mean $500,000,000
                  principal amount of the Company's 6.15% Series A Convertible
                  Subordinated Notes due March 16, 2010 issued pursuant to the
                  New 6.15% Notes Indenture.

                           "SERIES B CONVERTIBLE NOTES" shall mean $475,281,000
                  principal amount of the Company's 6.15% Series B Convertible
                  Subordinated Notes due March 16, 2010 issued pursuant to the
                  New 6.15% Notes Indenture.

                  (b)      Section 1 of the Notes Registration Rights Agreement
is hereby amended by amending and restating the following definitions in their
entirety to read as follows:

                  "CONVERTIBLE NOTES" shall mean the New 6.15% Notes and the New
         Convertible Notes.

                  "EQUITY REGISTRATION RIGHTS AGREEMENT" shall mean that certain
         Equity Registration Rights Agreement, dated as of March 6, 2000, as
         amended by Amendment No. 1 to Registration Rights Agreement, dated as
         of October 1, 2001, by and among the Company and the Purchaser, as such
         agreement may be further amended, modified or supplemented from time to
         time.

                  "HOLDER" shall mean the Purchaser and any transferee of the
         Purchaser to whom Registrable Securities have been transferred, other
         than a transferee to whom such Registrable Securities have been
         transferred pursuant to a Public Resale and who continues to be
         entitled to the rights of a Holder hereunder.

                  "STOCKHOLDERS AGREEMENT" shall mean the Amended and Restated
         Stockholders Agreement, dated as of October 1, 2001, by and among the
         Company, the Purchaser and the stockholders of the Company listed on
         Schedule I thereto, as such agreement may be amended, modified or
         supplemented from time to time.

                  (c)      The second sentence of Section 2(a) of the Notes
Registration Rights Agreement shall be amended by inserting the following clause
after "as expeditiously as possible," and before "file with the SEC": "but in
any event no later than thirty (30) days (excluding any days which occur during
a permitted Blackout Period under Section 5 below) after receipt of a written
request for a Demand Registration,".

                  (d)      The proviso contained in the second sentence of
Section 2(a) of the Notes Registration Rights Agreement is hereby amended by
replacing "$100,000,000" with "$10,000,000."

                  (e)      The first sentence of Section 2(c) of the Notes
Registration Rights Agreement is hereby amended and restated in its entirety to
read as follows:

                  "Holders shall be entitled to five (5) registrations of
Registrable Securities pursuant to this Section 2."


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                  (f)      Section 4 of the Notes Registration Rights Agreement
shall be renamed Section 4(a) and a new Section 4(b) of the Notes Registration
Rights Agreement shall be added to read as follows:

                           "(b) If (i) any Shelf Registration Statement has not
                  been declared effective by the SEC on or prior to the date on
                  which such Shelf Registration Statement is required to be
                  declared effective pursuant to Section 4(a), or (ii) the Shelf
                  Registration Statement is filed and declared effective but
                  shall thereafter cease to be effective at any time within the
                  time period required for effectiveness in Section 4(a) above
                  without being succeeded immediately by a post-effective
                  amendment to the Shelf Registration Statement that cures such
                  failure and that is itself immediately declared effective
                  (each such event referred to in clauses (i) and (ii), a
                  "REGISTRATION DEFAULT"), the Company shall pay liquidated
                  damages ("LIQUIDATED DAMAGES") to the Purchaser in an amount
                  equal to $0.01 per share of Registrable Securities covered by
                  such Shelf Registration Statement for each week or portion
                  thereof during which any Registration Default continues (other
                  than with respect to any period during which the Purchaser is
                  required to discontinue the disposition of Registrable
                  Securities pursuant to the Section 5 hereof). The amount of
                  such Liquidated Damages shall increase on each 90-day
                  anniversary of the day the first Registration Default occurred
                  by an additional $0.01 per share of Registrable Securities
                  covered by such Shelf Registration Statement for each week or
                  portion thereof during which any Registration Default
                  continues until all Registration Defaults have been cured, up
                  to a maximum amount of Liquidated Damages of $0.05 per week or
                  portion thereof per share of Registrable Securities covered by
                  such Shelf Registration Statement. All accrued Liquidated
                  Damages shall be paid by wire transfer of immediately
                  available funds or by federal funds check on the last day of
                  each four week period to an account previously designated in
                  writing to the Company by the Purchaser. Following the cure of
                  all Registration Defaults relating to any particular
                  Registrable Security, the accrual of Liquidated Damages with
                  respect to such Registrable Security will cease.

                           All obligations of the Company set forth in the
                  preceding paragraph that are outstanding with respect to any
                  Registrable Security at the time such security ceases to be a
                  Registrable Security shall survive until such time as all such
                  obligations have been paid in full."

                  (g)      Sections 6(a) through 6(n) of the Notes Registration
Rights Agreement are hereby amended by replacing "the Shelf Registration," in
each instance in which such clause appears, with "any Shelf Registration," and
by replacing "the Shelf Registration Statement," in each instance in which such
clause appears, with "any Shelf Registration Statement."


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                  (h)      Section 6(n) of the Notes Registration Rights
Agreement is hereby amended by replacing "$100,000,000" with "$10,000,000."

                  (i)      Section 9 of the Notes Registration Rights Agreement
shall be renamed Section 9(A), and a new Section 9(b) shall be added to read as
follows:

                           "(b)     The Company agrees (1) not to effect any
                  public or private offer, sale or distribution of any of its
                  equity securities or any class or series of its capital stock
                  having a preference in liquidation or with respect to
                  dividends, including a sale pursuant to Regulation D under the
                  Securities Act (other than any such sale or distribution of
                  such securities in connection with any merger or consolidation
                  by the Company or any subsidiary of the Company or the
                  acquisition by the Company or a subsidiary of the Company of
                  the capital stock or substantially all the assets of any other
                  Person or in connection with any employee stock option or
                  other benefit plan), during the 10-day period prior to, and
                  during the 90-day period beginning with, the effectiveness of
                  any Registration Statement to the extent timely notified in
                  writing by a Holder of Registrable Securities or the managing
                  underwriters in an underwritten offering (except as part of
                  such underwritten offering if permitted, or pursuant to
                  registrations on Forms S-4 or S-8 or any successor form to
                  such Registration Statement forms) and (2) during the
                  aforementioned period to use reasonable best efforts to cause
                  each Holder of each of its privately placed equity securities
                  or any class or series of its capital stock having a
                  preference in liquidation or with respect to dividends
                  purchased from the Company at any time on or after the date of
                  this Agreement to agree not to effect any public sale or
                  distribution of any such securities during such period,
                  including a sale pursuant to Rule 144 under the Securities Act
                  (except as part of such registration, if permitted)."

                  (j)      The last sentence of the provision that is hereby
renamed SECTION 9(a) of the Notes Registration Rights Agreement is hereby
amended by inserting "and if the Company and its directors, officers and other
significant stockholders enter into similar agreements" at the end of such
sentence.

                  (k)      Section 13(d) of the Notes Registration Rights
Agreement is hereby amended and restated in its entirety to read as follows:

                  "(d)     SUCCESSORS AND ASSIGNS. This Agreement shall inure to
                  the benefit of and be binding upon the successors and assigns
                  of each of the parties hereto including any person to whom
                  Registrable Securities are transferred, other than a
                  transferee to whom any such Registrable Securities have been
                  transferred pursuant to a Public Resale."


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                  SECTION 2.        MISCELLANEOUS.

                  (a)      This Amendment shall become effective upon its
execution and delivery by the Company and the Purchaser.

                  (b)      On and after the date hereof each reference in the
Notes Registration Rights Agreement to "this Agreement," "herein" or words of
like import shall mean and be a reference to the Notes Registration Rights
Agreement as amended hereby. No reference to this Amendment need be made in any
instrument or document at any time referring to the Notes Registration Rights
Agreement. A reference to the Notes Registration Rights Agreement in any such
instrument or document shall be deemed to be a reference to the Notes
Registration Rights Agreement as amended hereby. Except as expressly amended
hereby, in all other respects the Notes Registration Rights Agreement shall
remain in full force and effect.

                  (c)      This Amendment shall be governed by, construed and
enforced in accordance with the laws of the State of New York without giving
effect to the conflicts of laws provisions thereof. Each of the parties hereby
submits to personal jurisdiction and waives any objection as to venue in the
County of New York, State of New York. Service of process on the parties in any
action arising out of or relating to this Agreement shall be effective if mailed
to the parties in accordance with Section 13(c) of the Notes Registration Rights
Agreement. The parties hereto waive all right to trial by jury in any action or
proceeding to enforce or defend any rights hereunder.

                  (d)      This Amendment may be executed in any number of
counterparts, each of which shall be deemed to be an original, but all of which
together shall constitute but one and the same instrument.

                        [SIGNATURES APPEAR ON NEXT PAGE]


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                  IN WITNESS WHEREOF, the parties have executed this Amendment
as of the date first written above.

                                 METROMEDIA FIBER NETWORK, INC.


                                 By: /s/ Nick Tanzi
                                    --------------------------------------
                                       Name:  Nick Tanzi
                                       Title: President & CEO



                                 VERIZON INVESTMENTS INC.



                                 By: /s/ Phil Seskin
                                    --------------------------------------
                                       Name:  Phil Seskin
                                       Title: Senior Vice-President