| Election Name: | 1978 United States Senate election in New Hampshire |
| Country: | New Hampshire |
| Flag Year: | 1931 |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1972 United States Senate election in New Hampshire |
| Previous Year: | 1972 |
| Next Election: | 1984 United States Senate election in New Hampshire |
| Next Year: | 1984 |
| Election Date: | November 7, 1978 |
| Image1: | File:Gordon J. Humphrey (cropped).jpg |
| Nominee1: | Gordon J. Humphrey |
| Party1: | Republican Party (United States) |
| Popular Vote1: | 133,745 |
| Percentage1: | 50.71% |
| Nominee2: | Thomas J. McIntyre |
| Party2: | Democratic Party (United States) |
| Popular Vote2: | 127,945 |
| Percentage2: | 48.51% |
| U.S. Senator | |
| Before Election: | Thomas J. McIntyre |
| Before Party: | Democratic Party (United States) |
| After Election: | Gordon J. Humphrey |
| After Party: | Republican Party (United States) |
The 1978 United States Senate election in New Hampshire took place on November 7, 1978. Incumbent Democratic Senator Thomas J. McIntyre ran for re-election to a fourth term but was defeated by Republican Gordon J. Humphrey.