He played in Major League Baseball (MLB) for the Los Angeles Dodgers, Colorado Rockies, Oakland Athletics and Texas Rangers.

Out of pitchers, Rockies manager, Buddy Bell, asked injured catcher, Brent Mayne, who was unable to swing a bat due to a sprained left wrist, if he could pitch.

The following inning, with two outs and the bases loaded, Melhuse, pinch hitting for Mayne, singled off of Stan Belinda over shortstop Walt Weiss' head to win the game in walk-off fashion by a score of 8-7.

He would spend four seasons with the club as a backup to Damian Miller and later Jason Kendall, with his best year coming in 2004 when he hit .257/.309/.463 with 11 home runs and 31 RBI in 69 games.

Adam's career as a Texas Ranger was short-lived, as the club traded for fellow catcher Jarrod Saltalamacchia on July 31, 2007, which lessened Melhuse's playing time.

He made the team out of spring training as a backup to starting catcher Gerald Laird, but injured his hand in a game against the Detroit Tigers on April 24, resulting in his release.