The outfielder played in 64 games for the Pittsburgh Pirates of Major League Baseball during 1953 and 1955 and all or parts of 14 years in his native country.

Born in Monterrey, Nuevo León, Mexico, and nicknamed "Clipper", he threw and batted left-handed; he was listed as 6 feet 2 inches (1.88 m) tall and 185 pounds (84 kg).

Counting his service in the U.S. minor leagues, Montemayor played 21 seasons of professional baseball.

Montemayor made his major league debut on April 14, 1953, and hit a fly-ball out against Joe Black of the Brooklyn Dodgers.

During his MLB career Montemayor batted .173, with 26 hits; five doubles and three triples accompanied his two homers.