OPINION OF AKIN, GUMP, STRAUSS, HAUER & FELD, LLP

EXHIBIT 5.1


[AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P. LETTERHEAD]

June 20, 2000


Quanta Services, Inc.
1360 Post Oak Blvd., Suite 2100
Houston, Texas 77056

Gentlemen:

We have acted as counsel to Quanta Services, Inc., a Delaware
corporation (the "Company"), in connection with the filing of a registration
statement on Form S-3 (the "Registration Statement") with the Securities and
Exchange Commission pursuant to the Securities Act of 1933, as amended (the
"Securities Act"), for the registration of the sale from time to time pursuant
to Rule 415 under the Securities Act of up to $500,000,000 aggregate amount of
(i) subordinated debt securities and senior debt securities of the Company
(collectively, the "Debt Securities"), (ii) preferred stock, par value $.00001
per share, of the Company (the "Preferred Stock") which may be issued in the
form of depositary shares evidenced by depositary receipts (the "Depositary
Shares"), (iii) common stock, par value $.00001 per share, of the Company (the
"Common Stock"), and (iv) warrants of the Company to purchase Common Stock (the
"Warrants").

The senior Debt Securities are to be issued pursuant to an Indenture
(the "Senior Indenture") between the Company and Chase Bank of Texas, National
Association, as trustee. The subordinated Debt Securities are to be issued
pursuant to an Indenture (the "Subordinated Indenture") between the Company and
Chase Bank of Texas, National Association, as trustee. Chase Bank of Texas,
National Association, in its capacity as trustee under the Senior Indenture and
the Subordinated Indenture is referred to herein as the "Trustee" and the Senior
Indenture and the Subordinated Indenture are referred to herein collectively as
the "Indentures."

We have, as counsel, examined such corporate records, certificates and
other documents and reviewed such questions of law as we have deemed necessary,
relevant or appropriate to enable us to render the opinions expressed below. In
rendering such opinions, we have assumed the genuineness of all signatures and
the authenticity of all documents examined by us. As to various questions of
fact material to such opinion, we have relied upon representations of the
Company.

In connection with this opinion, we have assumed: (i) the Registration
Statement, and any amendments thereto (including post-effective amendments),
have become effective and shall not have been terminated or rescinded; (ii) a
Prospectus Supplement will have been prepared and filed with the Commission
describing any Securities offered thereby; (iii) all Securities will be


Quanta Services, Inc.
June 20, 2000
Page 2


issued and sold in compliance with applicable federal and state securities laws
and in the manner stated in the Registration Statement and the applicable
Prospectus Supplement; (iv) each Indenture governing the Debt Securities, each
Depositary Agreement relating to the Depositary Shares and each Warrant
Agreement relating to the Warrants will be duly authorized, executed and
delivered by the parties thereto in substantially the form reviewed by us; (v)
each Indenture will have been duly qualified under the Trust Indenture Act of
1939, as amended; (vi) at the time of any offering or sale of any shares of
Common Stock or Preferred Stock, the Company will have the number of shares of
Common Stock or Preferred Stock, as set forth in the Prospectus Supplement
relating to such offering or sale, duly authorized, established (if applicable)
and available for issuance; (vii) a definitive purchase, underwriting or similar
agreement with respect to any Securities offered will have been duly authorized
and validly executed and delivered by the Company and the other parties thereto;
(viii) Securities issuable upon conversion, exchange or exercise of any
Securities being offered will have been duly authorized, established (if
appropriate) and reserved for issuance upon such conversion, exchange or
exercise and (ix) there shall not have occurred any change in law affecting the
validity or enforceability of any of such Security.

Based upon such examination and representations, we advise you that, in
our opinion:

1. When (i) the terms of the Debt Securities have been duly established in
accordance with the applicable Indenture and the applicable supplemental
indenture relating to such Debt Securities so as not to violate any applicable
law or result in a default under or breach of any agreement or instrument
binding upon the Company and so as to comply with any requirement or restriction
imposed by any court or governmental or regulatory body having jurisdiction over
the Company, and (ii) the Debt Securities have been duly executed and
authenticated in accordance with the applicable Indenture and the applicable
supplemental indenture relating to such Debt Securities and duly issued and
delivered by the Company in the manner contemplated in the Registration
Statement and any prospectus supplement relating thereto, the Debt Securities
will constitute valid and binding obligations of the Company, enforceable in
accordance with their terms, except as (a) the enforceability thereof may be
limited by bankruptcy, insolvency, reorganization, fraudulent transfer,
moratorium or other similar laws now or hereafter in effect relating to or
affecting the enforcement of creditor's rights generally, and (b) the
availability of equitable remedies may be limited by equitable principles of
general applicability (regardless of whether considered in a proceeding at law
or in equity).

2. When (i) the terms of the Warrants and of their issuance and sale have been
duly established in conformity with the Warrant Agreement relating to such
Warrants so as not to violate any applicable law or result in a default under or
breach of any agreement or instrument binding upon the Company and so as to
comply with any requirement or restriction imposed by any court or governmental
or regulatory body having jurisdiction over the Company, and (ii) the Warrants
have been duly executed and countersigned in accordance with the Warrant
Agreement relating to such Warrants, and issued and sold in the form and in the
manner contemplated in the Registration Statement and any prospectus supplement
relating thereto, such Warrants will constitute valid and binding obligations of
the Company, enforceable in accordance with their terms, except as (a) the
enforceability thereof may be limited by bankruptcy, insolvency, reorganization,
fraudulent transfer, moratorium or other similar laws now or hereafter in effect


Quanta Services, Inc.
June 20, 2000
Page 3


relating to or affecting the enforcement of creditor's rights generally, and (b)
the availability of equitable remedies may be limited by equitable principles of
general applicability (regardless of whether considered in a proceeding at law
or in equity).

3. When (a) the Board of Directors of the Company (or a duly authorized
committee thereof) has taken all necessary corporate action to approve the
issuance and sale of any shares of any series of Preferred Stock (and Depositary
Shares, if applicable), and when such shares are paid for, issued and delivered
in accordance with the applicable underwriting or other agreement, such shares
will be validly issued, fully paid and non-assessable.

4. When the Board of Directors (or a duly authorized committee thereof) has
taken all necessary corporate action to authorize the issuance and sale of such
shares of Common Stock proposed to be sold by the Company, and when such shares
of Common Stock are issued and delivered in accordance with the applicable
underwriting or other agreement, such shares of Common Stock (including any
shares of Common Stock issued (i) upon exercise of any Warrants for Common
Stock, (ii) upon conversion of any Debt Securities that are convertible or
exchangeable for Common Stock, or (iii) upon the exchange or conversion of any
shares of Preferred Stock that are exchangeable or convertible into Common
Stock) will be validly issued, fully paid and non-assessable.

We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement. In addition, we consent to the reference to us under the
caption "Legal Matters" in the prospectus.

This opinion is rendered solely to you in connection with the above
matter. This opinion may not be relied upon by you for any other purpose or
relied upon by or furnished to any other person without our prior written
consent.

Very truly yours,



AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P.