Missouri held special elections on November 7, 2017, deciding 3 legislative seats.
Legislature
- House (163 seats): 46 D, 117 R before the election, 45 D, 111 R, 7 other or vacant after; control stayed with Republicans.
- Senate (34 seats): 9 D, 25 R before the election, 10 D, 23 R, 1 other or vacant after; control stayed with Republicans.
Legislative races
| Race | Winner | Others | Notes |
|---|---|---|---|
| House 23 | Barbara Washington (D) 88% | David Martin (R) 9.1%, Daniel Trott (G) 1.9% | |
| House 151 | Herman Morse (R) 70.5% | Curtis Clark (D) 27.2%, Rick Vandeven (L) 2.3% | |
| Senate 8 | Mike Cierpiot (R) 50.3% | Hillary Shields (D) 42.6%, Jacob Turk (I) 7.1% |