EXHIBIT 5.1

                                  May 4, 1999

Mr. Jose M. Sariego
Senior Vice President - General Counsel
MasTec, Inc.
3155 N.W. 77th Avenue
Miami, Florida 33122-1205

     Re:   MasTec, Inc.
           REGISTRATION STATEMENT ON FORM S-8

Dear Mr. Sariego:

         As counsel to MasTec, Inc., a Florida corporation (the "Corporation"),
we have examined the Articles of Incorporation and Bylaws of the Corporation, as
well as such other documents and proceedings as we have considered necessary for
the purposes of this opinion. We have also examined and are familiar with the
Corporation's Registration Statement on Form S-8 (the "Registration Statement"),
filed with the Securities and Exchange Commission under the Securities Act of
1933, as amended, relating to 1,100,000 shares of the Corporation's common
stock, par value $.10 per share (the "Common Stock"), issuable by the
Corporation pursuant to the Non-Employee Directors' Stock Plan and the 1999
Non-Qualified Employee Stock Option Plan (the "Plans").



Mr. Jose M. Sariego
May 4, 1999
Page 2


         In rendering this opinion, we have assumed, without independent
investigation: (i) the authenticity of all documents submitted to us as
originals; (ii) the conformity to original documents of all documents submitted
to us as certified or photostatic copies and (iii) the genuineness of all
signatures. In addition, as to questions of fact material to the opinions
expressed herein, we have relied upon such certificates of public officials,
corporate agents and officers of the Corporation and such other certificates as
we deemed relevant.

         Based upon the foregoing, and having regard to legal considerations
which we deem relevant, we are of the opinion that following the issuance and
delivery of the Common Stock by the Corporation under the Plan, against payment
of adequate consideration therefor to the Corporation in accordance with the
terms of the Plans, the Common Stock will be validly issued, fully paid and
non-assessable.

         This opinion is intended solely for the Corporation's use in connection
with the registration of the Common Stock and may not be relied upon for any
other purpose or by any other person. This opinion may not be quoted in whole or
in part or otherwise referred to or furnished to any other person except in
response to a valid subpoena. This opinion is limited to the matters expressly
stated herein, and no opinion is implied or may be inferred beyond the matters
expressly stated herein. This opinion is rendered as of the date hereof, and we
assume no obligation to update or supplement such opinion to reflect any facts
or circumstances that may hereafter come to our attention or any changes in
facts or laws that may hereafter occur. We hereby consent to the inclusion of
this opinion letter as an exhibit to the Registration Statement.


                                         Very truly yours,



                                         STEARNS WEAVER MILLER WEISSLER
                                         ALHADEFF & SITTERSON, P.A.