| Election Name: | 1938 United States Senate election in Iowa |
| Country: | Iowa |
| Flag Image: | Flag of Iowa (xrmap collection).svg |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1936 United States Senate special election in Iowa |
| Previous Year: | 1936 (special) |
| Next Election: | 1944 United States Senate election in Iowa |
| Next Year: | 1944 |
| Election Date: | November 8, 1938 |
| Image1: | File:Guy Mark Gillette.jpg |
| Nominee1: | Guy M. Gillette |
| Party1: | Democratic Party (United States) |
| Popular Vote1: | 413,788 |
| Percentage1: | 49.74% |
| Nominee2: | Lester J. Dickinson |
| Party2: | Republican Party (United States) |
| Popular Vote2: | 410,983 |
| Percentage2: | 49.41% |
| Map Size: | 240px |
| U.S. Senator | |
| Before Election: | Guy M. Gillette |
| Before Party: | Democratic Party (United States) |
| After Election: | Guy M. Gillette |
| After Party: | Democratic Party (United States) |
The 1938 United States Senate election in Iowa took place on November 8, 1938. Incumbent Democratic Senator Guy M. Gillette, who won a special election to complete the unexpired term of Richard Louis Murphy, won a full term in office by defeating Republican former Senator Lester J. Dickinson. Gillette and Dickinson had briefly served together in the final months of 1936.
Primary elections were held on June 6. Gillette overcame a primary challenge from U.S. Representative Otha Wearin, who was personally recruited by President Franklin D. Roosevelt given Gillette's opposition to New Deal programs.[1] Dickinson defeated Representative Lloyd Thurston for the Republican nomination.