The 2008 United States Senate elections were held on November 4, 2008, with 35 of the 100 seats in the Senate being contested. Thirty-three seats were up for regular elections; the winners were eligible to serve six-year terms from January 3, 2009, to January 3, 2015, as members of Class 2. There were also two special elections, the winners of those seats would finish the terms that ended on January 3, 2013. The presidential election, which was won by Democrat Barack Obama, elections for all House of Representatives seats; elections for several gubernatorial elections; and many state and local elections occurred on the same date.

The 2008 United States House of Representatives elections were held on November 4, 2008, to elect members to the United States House of Representatives to serve in the 111th United States Congress from January 3, 2009, until January 3, 2011. It coincided with the election of Barack Obama as president. All 435 voting seats, as well as all 6 non-voting seats, were up for election. The Democratic Party, which won a majority of seats in the 2006 election, expanded its control in 2008.