The 1887 Ilkeston by-election was held on 24 March 1887 after the death of the incumbent Liberal MP Thomas Watson. The election was won by the Liberal candidate, Sir Balthazar Walter Foster.
| Party | Candidate | Votes | % | ±% | |
|---|---|---|---|---|---|
| Liberal | Sir Balthazar Walter Foster | 5,512 | 56.9 | +2.0 | |
| Conservative | Samuel Leeke | 4,180 | 43.1 | −2.0 | |
| Majority | 1,332 | 13.8 | +4.0 | ||
| Turnout | 9,692 | 88.5 | +9.6 | ||
| Liberal hold | Swing | +2.0 | |||