MasTec (MTZ) 10-Q 2006 Q3 Quarterly report

Exhibit 32.1

CERTIFICATION PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of MasTec, Inc. (the “Company”) on Form 10-Q for the period ended September 30, 2006 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Austin J. Shanfelter, President and Chief Executive Officer of MasTec, Inc., certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to the best of my knowledge:

(1)	The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and
(2)	The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: November 9, 2006

/s/ Austin J. Shanfelter  

Austin J. Shanfelter 

President and Chief Executive Officer
(Principal Executive Officer) 

The certification set forth above is being furnished as an exhibit solely pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 and is not being filed as part of the Quarterly Report on Form 10-Q for the period ended September 30, 2006, or as a separate disclosure documents of we or the certifying officers.