Hamilton made his MLB debut on June 3, 1988, as a defensive replacement for Robin Yount in the top of the seventh against the California Angels. In his first at-bat, in the bottom of the inning, he singled to center field off of Stew Cliburn of the Angels for his first major league hit. He hit his first home run off of Bret Saberhagen of the Kansas City Royals on July 19, 1988. In 44 games with the Brewers during the second half of the 1988 season, Hamilton hit .184. His most notable moment that season was during his first start in left field, on September 3, he collided with shortstop Dale Sveum while chasing a blooper over third base. They collided with such force that Sveum's leg snapped, causing him to miss the rest of the season and all of the 1989 season and derailing his career. Hamilton avoided injury but spent the entire 1989 season back in the minors with the Zephyrs, where he hit .286 in 129 games.