The 1980 United States Senate election in Iowa was held on November 4, 1980. Incumbent Democratic United States Senator John Culver ran for reelection to a second term, but lost to Republican nominee Chuck Grassley, the United States Congressman from Iowa's 3rd congressional district. This election marked the beginning of, as of 2022, 8 consecutive victories for Grassley in the Senate, and remains the closest election of his Senate career.