How many NCAA division 1 basketball teams have gone undefeated?

1 time 1974-75 bob knights Indiana hoosiers

Actually, UNLV did it in 1990-91 (for the regular season). There stil could be others, I haven't researched it.

Actually UCLA did it at least 4 times: 1963-64, 1966-67, 1971-72, and 1997-73. I say "at least" 4 times since my reference only lists undefeated seasons that include the tournament, so I'm not 100% sure that there were no additional undefeated regular seasons.

Actually, North Carolina did it in 1924 and 1957, winning national championships in both seasons (the '24 one is sometimes disputed due to how it was received...the Helms Foundation at that time voted a team to be the national champion).