Swimming at the 2009 World Aquatics Championships – Men's 4 × 100 metre freestyle relay
The men's 4×100 m freestyle relay at the 2009 World Aquatics Championships took place on 26 July 2009 at the Foro Italico in Rome, Italy.
Records
The existing records when the event started were:| Record | Swimmers | Time | Location |
| World record | Michael Phelps Garrett Weber-Gale Cullen Jones Jason Lezak | 3:08.24 |  Beijing 2008 |
| Championship record | Michael Phelps Neil Walker Cullen Jones Jason Lezak | 3:12.72 |  Melbourne 2007 |