The 1986 United States Senate election in Idaho took place on November 4, 1986 alongside other elections to the United States Senate in other states as well as elections to the United States House of Representatives and various state and local elections. Incumbent Republican U.S. Senator Steve Symms narrowly won re-election to a second term. As of 2024, this is the last time that a U.S. Senate race in Idaho was decided by a single-digit margin. This was the first time since 1926 that an incumbent Republican Senator was re-elected to this seat.