The 2008 United States Senate election in Iowa was held on November 4, 2008. Incumbent Senator Tom Harkin sought re-election to a fifth and final term in office. Unlike Harkin's three previous reelection bids, he was not challenged by a sitting United States Congressman but instead faced small businessman Christopher Reed, who won the Republican primary by just a few hundred votes. Harkin defeated Reed in a landslide, winning 94 of Iowa's 99 counties. , this is the last time that a Democrat has won a U.S. Senate election in Iowa.
Harkin won all five congressional districts, including two that elected Republicans.