| Election Name: | 1984 United States Senate election in Iowa |
| Country: | Iowa |
| Flag Image: | Flag of Iowa (xrmap collection).svg |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1978 United States Senate election in Iowa |
| Previous Year: | 1978 |
| Next Election: | 1990 United States Senate election in Iowa |
| Next Year: | 1990 |
| Election Date: | November 6, 1984 |
| Image1: | Tom Harkin 1979 congressional photo.jpg |
| Nominee1: | Tom Harkin |
| Party1: | Democratic Party (United States) |
| Popular Vote1: | 716,883 |
| Percentage1: | 55.46% |
| Nominee2: | Roger Jepsen |
| Party2: | Republican Party (United States) |
| Popular Vote2: | 564,381 |
| Percentage2: | 43.66% |
| Map Size: | 240px |
| U.S. Senator | |
| Before Election: | Roger Jepsen |
| Before Party: | Republican Party (United States) |
| After Election: | Tom Harkin |
| After Party: | Democratic Party (United States) |
The 1984 United States Senate election in Iowa was held on November 6, 1984. Incumbent Republican Senator Roger Jepsen ran for re-election to a second term in office. Jepsen was opposed by U.S. Representative Tom Harkin, from Iowa's 5th congressional district, who won the Democratic primary uncontested.
The general election was full of mudslinging and personal attacks, including the embellishment by both candidates of their military records; Harkin attacked Jepsen for failing to keep his promise to not sell AWACS aircraft to Saudi Arabia.[1] Ultimately, Harkin defeated Jepsen by a comfortable margin of nearly 12 points, winning the first of five terms in the Senate. This is the last time that a Senator from Iowa lost re-election.