Swimming at the 2007 World Aquatics Championships – Men's 4 × 100 metre medley relay

The men's 4 × 100 metre medley relay at the 2007 World Aquatics Championships took place on 1 April 2007 at the Rod Laver Arena in Melbourne, Australia. The top-12 finishers from this race qualified for the event at the 2008 Olympics.

The existing records when the event started were:
 * World record (WR): 3:30.68, USA (Peirsol, Hansen, Crocker, Lezak), 21 August 2004 in Athens, Greece.
 * Championship record (CR): 3:31.54, (USA) (Peirsol, Hansen, Crocker, Lezak), Barcelona 2003 (27 July 2003)