Gaetti then spent the next three years in the Twins' minor league system, playing for the rookie level Elizabethton Twins in the Appalachian League in 1979, the A-level Wisconsin Rapids Twins in the Midwest League in 1980, and the AA-level Orlando Twins in the Southern League in 1981. Gaetti then made his major league debut in nine September games and he hit a home run off of Charlie Hough in his first major league at bat. In 1982, Gaetti would become a permanent fixture at third base for the Twins and would man third base in Minnesota for the next nine seasons.