The 1989–90 Idaho Vandals men's basketball team represented the University of Idaho during the 1989–90 NCAA Division I men's basketball season. Members of the Big Sky Conference, the Vandals were led by second-year head coach Kermit Davis and played their home games on campus at the Kibbie Dome in Moscow, Idaho. Seeded thirteenth again in the West Regional, Idaho lost to Louisville by nineteen points in Salt Lake City in the first round. Davis left in late March for Texas A&M, and was succeeded by Larry Eustachy, a former fellow UI assistant in Tim Floyd's first season (1986–87).