EXHIBIT 5.1

                                December 21, 1999



Teligent, Inc.
8065 Leesburg Pike, Suite 400
Vienna, Virginia 22182

Dear Sirs and Madams:

         We have acted as counsel to Teligent, Inc., a Delaware corporation (the
"Company"),  in connection  with the  preparation and filing by the Company of a
Registration  Statement  on Form S-8 (the  "Registration  Statement")  under the
Securities Act of 1933, as amended,  for the registration of 4,300,000 shares of
Class A Common Stock,  $0.01 par value per share (the "Shares"),  of the Company
which may be issued upon  exercise of stock  options  pursuant to the  Teligent,
Inc.  1997 Stock  Incentive  Plan and the Teligent,  Inc.  1999  Employee  Stock
Purchase Plan (collectively, the "Plans").

         We have examined and are familiar with  originals or copies,  certified
or  otherwise  identified  to our  satisfaction,  of such  documents,  corporate
records,  certificates of public  officials and officers of the Company and such
other  instruments as we have deemed necessary or appropriate as a basis for the
opinions expressed below.

         Based on the foregoing, we are of the opinion that:

              1. The issuance of the Shares upon exercise of stock options
granted under the Plans has been duly authorized; and

              2. When the Shares have been issued and delivered in accordance
with the terms of the Plans, the Shares will be legally issued, fully paid and
nonassessable.

         We hereby  consent to the filing of this  opinion as Exhibit 5.1 to the
Registration  Statement. In giving such consent, we do not thereby admit that we
come within the category of persons whose consent is required under Section 7 of
the  Securities  Act of 1933, as amended,  or the rules and  regulations  of the
Securities and Exchange Commission thereunder.


                                   Very truly yours,


                                   /S/ AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P.
                                   ---------------------------------------------
                                       AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P.