The 1938 United States Senate election in Wisconsin was held on November 8, 1938. IncumbentDemocratic U.S. Senator F. Ryan Duffy ran for a second term in office. In a three way race, Alexander Wiley defeated Duffy and Lieutenant Governor Herman L. Ekern.
Primary elections were held on September 20. Senator Duffy was unopposed for the Democratic nomination. The Republican primary was a rematch of the 1936 gubernatorial primary; Wiley defeated John B. Chapple, who had been nominated in the previous two Senate races. After losing, Chapple entered the general election as a candidate advocating for the Townsend Act. In the Progressive primary, Ekern defeated Thomas R. Amlie by roughly 9,091 votes.[1]