Swimming at the 2001 World Aquatics Championships – Men's 4 × 100 metre medley relay

The men's 4 × 100 metre medley relay event at the 2001 World Aquatics Championships took place in Marine Messe in Fukuoka, Japan in 28 July 2001.

Records
Prior to the competition, the existing world and championship records were as follows.

The following record was established during the competition: