| Election Name: | 1966 United States Senate election in Iowa |
| Country: | Iowa |
| Flag Image: | Flag of Iowa (xrmap collection).svg |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1960 United States Senate election in Iowa |
| Previous Year: | 1960 |
| Next Election: | 1972 United States Senate election in Iowa |
| Next Year: | 1972 |
| Election Date: | November 8, 1966 |
| Image1: | File:SenatorJackMillerIA.jpg |
| Nominee1: | Jack Miller |
| Party1: | Republican Party (United States) |
| Popular Vote1: | 522,339 |
| Percentage1: | 60.92% |
| Nominee2: | E.B. Smith |
| Party2: | Democratic Party (United States) |
| Popular Vote2: | 324,114 |
| Percentage2: | 37.80% |
| Map Size: | 240px |
| U.S. Senator | |
| Before Election: | Jack Miller |
| Before Party: | Republican Party (United States) |
| After Election: | Jack Miller |
| After Party: | Republican Party (United States) |
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.