Which UFC event was the first to use five-minute rounds?

UFC 21 was the first UFC event to use five-minute rounds.

The event took place in Cedar Rapids, Iowa, on July 16, 1999. Its rule changes helped move UFC contests away from the brief, tournament-style bouts of the promotion’s earliest years and toward the structure familiar in modern MMA.

UFC 21 used five-minute rounds, with non-title fights scheduled for three rounds and title fights scheduled for five. The event also helped establish a clearer scoring framework for judges.

Five-minute rounds are now strongly associated with the UFC, but they were not part of the original format. Early events often used one long bout or tournament rounds with different time limits. UFC 21 therefore represents an important transition in the sport’s competitive and regulatory history.