The 2004–05 Illinois Fighting Illini men's basketball team marked the 100th season of men's basketball at the University of Illinois at Urbana–Champaign. After starting the regular season with a record of 29–0 and winning the Big Ten Conference regular season title outright at 15–1, the Illini were Big Ten tournament champions. They advanced in the NCAA tournament to the national championship, marking the school's first appearance in the championship game, but lost to North Carolina, 75–70. They ended the season at 37–2, tying the record for most victories in a season for a men's college basketball team.