The May Bumps 2004 were a set of rowing races held at Cambridge University from Wednesday 9 June 2004 to Saturday 12 June 2004. The event was run as a bumps race and was the 113th set of races in the series of May Bumps which have been held annually in mid-June since 1887. In 2004, a total of 171 crews took part (94 men's crews and 77 women's crews), with around 1500 participants in total.