The men's 4 x 100 metres relay at the 2009 World Championships in Athletics took place at the Olympic Stadium in Berlin on August 21 and August 22. The two main contenders for the event were the reigning World Champions, the United States, and the reigning Olympic Champions, Jamaica. Jamaica held the world record at 37.10 (which was later rescinded), which was established at the 2008 Summer Olympics in Beijing, while the United States entered with the 2009 overall season-best 37.85.