Exhibit 8.1


               [LETTERHEAD OF PAUL, WEISS, RIFKIND, WHARTON & GARRISON]








(212) 373-3000


                                                  January 25, 1999







Metromedia Fiber Network, Inc.
1 North Lexington Avenue
White Plains, NY 10601

          Re:  Metromedia Fiber Network, Inc.
               $650,000,000 10% Series B
               Senior Notes Due 2008
               -----------------------------------

Dear Sir or Madam:

          We have acted as special United States federal tax counsel for 
Metromedia Fiber Network, Inc. (the "Company") in connection with the offer 
to exchange $650,000,000 aggregate principal amount of the Company's 10% 
Series B Senior Notes due 2008 (the "Exchange Notes"), which have been 
registered under the United States Securities Act of 1933, as amended (the 
"Securities Act"), for a like aggregate principal amount of outstanding 10% 
Series A Senior Notes due 2008 (the "Exchange Offer").

          We are giving this opinion in connection with the Registration
Statement on Form S-4, as amended (the "Registration Statement"), relating to
the registration by the Company of the Exchange Notes to be offered in the
Exchange Offer, filed by the Company with the Securities and Exchange Commission
(the "Commission") pursuant to the Securities Act and the rules and regulations
of the



Metromedia Fiber Network, Inc.                                                 2

Commission promulgated thereunder.  Capitalized terms used but not defined
herein have the respective meanings ascribed to them in the Registration
Statement. 

          In rendering our opinion, we have examined originals or copies,
certified or otherwise identified to our satisfaction, of such agreements and
other documents as we have deemed relevant and necessary and we have made such
investigations of law as we have deemed appropriate as a basis for the opinion
expressed below.  In our examination, we have assumed the authenticity of
original documents, the accuracy of copies and the genuineness of signatures. 
We understand and assume that each such agreement represents the valid and
binding obligation of the respective parties thereto, enforceable in accordance
with its respective terms and the entire agreement between the parties with
respect to the subject matter thereof, (ii) the parties to each agreement have
complied, and will comply, with all of their respective covenants, agreements
and undertakings contained therein and (iii) the transactions provided for by
each agreement were and will be carried out in accordance with their terms.

          Our opinion is based upon existing United States federal income and
estate tax laws, regulations, administrative pronouncements and judicial
decisions.  All such authorities are subject to change, either prospectively or
retroactively, and any such change could affect our opinion.

          The opinion set forth herein has no binding effect on the United
States Internal Revenue Service or the courts of the United States.  No
assurance can be given that, if the matter were contested, a court would agree
with the opinion set forth herein.

          We hereby confirm the opinion set forth under the caption "Certain
United States Federal Tax Considerations" in the Registration Statement.  While
such description discusses the material anticipated United States federal income
tax consequences applicable to certain holders of Notes, it does not purport to
discuss all United States federal income tax considerations and our opinion is
limited to those United States federal income tax considerations specifically
discussed therein.

          In giving the foregoing opinion, we express no opinion other than as
to the federal income tax laws of the United States of America.

          We are furnishing this letter in our capacity as special United States
tax counsel to the Company.  This letter is not to be used, circulated, quoted
or otherwise referred to for any other purpose, except as set forth below.




Metromedia Fiber Network, Inc.                                                 3



          We hereby consent to the filing of this opinion as Exhibit 8.1 to the
Registration Statement and we further consent to the use of our name under the
caption "Certain United States Federal Tax Considerations" in the Registration
Statement.  The issuance of such a consent does not concede that we are an
"expert" for purposes of the Securities Act.

                                   Very truly yours,

                      /s/ Paul, Weiss, Rifkind, Wharton & Garrison

                         PAUL, WEISS, RIFKIND, WHARTON & GARRISON