The 1898 South East Durham by-election was held on 3 February 1898 after the death of the incumbent Liberal Unionist MP, Sir Henry Marshman Havelock-Allan. The seat was gained by the Liberal candidate, Joseph Richardson, although the unsuccessful Liberal Unionist candidate Frederick William Lambton would regain the seat for the Liberal Unionists in the 1900 general election.
| Party | Candidate | Votes | % | ±% | |
|---|---|---|---|---|---|
| Liberal | Joseph Richardson | 6,286 | 51.1 | +1.6 | |
| Liberal Unionist | Frederick William Lambton | 6,011 | 48.9 | −1.6 | |
| Majority | 275 | 2.2 | N/A | ||
| Turnout | 12,297 | 82.8 | +2.3 | ||
| Liberal gain from Liberal Unionist | Swing | +1.6 | |||