| Election Name: | 1978 United States Senate election in Oregon |
| Country: | Oregon |
| Flag Year: | 1931 |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1972 United States Senate election in Oregon |
| Previous Year: | 1972 |
| Next Election: | 1984 United States Senate election in Oregon |
| Next Year: | 1984 |
| Election Date: | November 7, 1978 |
| Image1: | File:Mark Hatfield – 1967 (cropped).jpg |
| Nominee1: | Mark Hatfield |
| Party1: | Republican Party (United States) |
| Popular Vote1: | 550,615 |
| Percentage1: | 61.66% |
| Nominee2: | Vernon Cook |
| Party2: | Democratic Party (United States) |
| Popular Vote2: | 341,616 |
| Percentage2: | 38.26% |
| Map Size: | 250px |
| U.S. Senator | |
| Before Election: | Mark Hatfield |
| Before Party: | Republican Party (United States) |
| After Election: | Mark Hatfield |
| After Party: | Republican Party (United States) |
The 1978 United States Senate election in Oregon took place on November 7, 1978. Incumbent Republican Senator Mark Hatfield was re-elected to a third term in office, defeating Democrat Vernon Cook.