In his three years as first baseman for the University of Tampa, Martinez was a three-time first-team all-SSC, all-South Region and All-America pick, in addition to being selected to the Academic All-America team. Playing in his hometown of Tampa, he broke school records for batting average (.398), home runs (54) and runs batted in (222). In 1988, he was a finalist for the Golden Spikes Award, which is given to the top collegiate baseball player in the nation at any division level. Martinez was a member of the USA team that won the 1988 Olympic gold medal in baseball in Korea, and was most valuable player of the World Amateur Championships in Italy in 1988. That same year he was also named Tampa Sports Club Amateur Athlete of the Year. Martinez was selected in the first round (14th pick overall) of the 1988 draft by the Seattle Mariners. He also helped the New York Yankees win the World Series in 1996 and 1998-2000. He also made the 1995 and 1997 All-Star rosters.