New Hampshire held special elections on November 7, 2017, deciding 5 legislative seats across 3 districts.
Legislature
- House (400 seats): 175 D, 225 R before the election, 177 D, 220 R, 3 other or vacant after; control stayed with Republicans.
- Senate (24 seats): 10 D, 14 R before the election, 10 D, 14 R after; control stayed with Republicans.
Legislative races
| Race | Winner | Others | Notes |
|---|---|---|---|
| House Hillsborough-15 | Erika Connors (D) 50.5% | Albert MacArthur Jr. (R) 49.5% | Flipped R to D |
| House Sullivan-1 | Brian M. Sullivan (D) | Margaret Drye (R) | |
| Senate 16 | Kevin Cavanaugh (D) 54.8% | David Boutin (R) 44%, Jason Allen Dubrow (L) 1.3% |