EXHIBIT 12.1 MASTEC, INC. AND SUBSIDIARIES Computation of Ratio of Earnings to Fixed Charges NINE MONTHS ENDED YEAR ENDED DECEMBER 31, SEPTEMBER 30, ------------------------------------------------------------------ --------------------------- 1992 1993 1994 1995 1996 1996 1997 --------- ---------- ----------- ---------- ----------- ----------- ------------ (Dollars in thousands) Income from continuing operations before income taxes........................... $9,581 $7,353 $10,291 $385 $50,719 $30,911 $52,927 Fixed Charges: Interest expense............... 98 302 3,846 5,306 11,940 8,577 8,413 Interest portion of rent expense........................ -- -- 1,157 1,362 1,681 1,690 1,980 --------- ---------- ----------- ---------- ----------- ----------- ------------ Total fixed charges............. 98 302 5,003 6,668 13,621 10,267 10,393 --------- ---------- ----------- ---------- ----------- ----------- ------------ Earnings (for purposes of fixed charges).................. 9,679 7,655 15,294 7,053 64,340 41,178 63,320 --------- ---------- ----------- ---------- ----------- ----------- ------------ Ratio of earnings to fixed charges......................... 98.8x 25.3x 3.1x 1.1x 4.7x 4.0x 6.1x