424B3: Prospectus filed pursuant to Rule 424(b)(3)

Prospectus Supplement No. 4 Filed Pursuant to Rule 424(b)(3)
(To Prospectus dated February 12, 2004) Registration Number 333-111738

$270,000,000

QUANTA SERVICES, INC.

4.50% CONVERTIBLE SUBORDINATED DEBENTURES DUE 2023
AND
THE COMMON STOCK ISSUABLE UPON CONVERSION OR REPURCHASE OF THE DEBENTURES

---------------------------------

This prospectus supplement relates to the resale by selling security
holders of our 4.50% Convertible Subordinated Debentures Due 2023 and the shares
of our common stock issuable upon the conversion or repurchase of the
debentures.

This prospectus supplement should be read in conjunction with, and may
not be delivered or utilized without, the prospectus dated February 12, 2004,
Supplement No. 1 to such prospectus dated March 8, 2004, Supplement No. 2 to
such prospectus dated March 26, 2004 and Supplement No. 3 to such prospectus
dated April 30, 2004. The terms of the debentures are set forth in the
prospectus.

THIS INVESTMENT INVOLVES RISKS. SEE "RISK FACTORS" BEGINNING ON
PAGE 5 OF THE PROSPECTUS.

Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if the
prospectus or this prospectus supplement is truthful or complete. Any
representation to the contrary is a criminal offense.

The information in the table appearing under the heading "Selling
Security Holders" in the prospectus is amended by adding the information below
with respect to persons not previously listed in the prospectus and by
supplementing the information with respect to other persons previously listed in
the prospectus that are listed below.