The 1966 United States Senate election in Iowa took place on November 8, 1966. Incumbent Republican Senator Jack Miller was re-elected to a second term in office over Democrat E.B. Smith.
After this race, no incumbent would be re-elected to either of Iowa's Senate seats until Chuck Grassley was elected to his second term 20 years later.
Following his loss, Hoover registered to run in the general election as the "Iowa Party" candidate.