The 2004 United States House of Representatives elections were held on November 2, 2004, to elect all 435 seats of the chamber. It coincided with the re-election of President George W. Bush as well as many Senate elections and gubernatorial elections. Prior to the election in the 108th Congress, Republicans held 227 seats, Democrats held 205, with two Republican vacancies and one independent. As a result of this election, the 109th Congress began composed of 232 Republicans, 201 Democrats, one independent, and one vacancy.

The 2004 United States Senate elections were held on November 2, 2004, with all Class 3 Senate seats being contested. They coincided with the re-election of George W. Bush as president and the United States House elections, as well as many state and local elections. Senators who were elected in 1998, known as Senate Class 3, were seeking re-election or retiring in 2004.