The following table contains the by-elections that have occurred during the term of the 17th Parliament.
| Electorate and by-election | Date | Incumbent | Cause | Winner | |||
|---|---|---|---|---|---|---|---|
| Thames | 1909 | 4 February | James McGowan | Appointed to Legislative Council | Edmund Taylor | ||
| Northern Maori | 1909 | 20 March | Hone Heke Ngapua | Death | Peter Buck | ||
| Rangitikei | 1909 | 16 September | Arthur Remington | Death | Robert Smith | ||
| Auckland East | 1910 | 16 June | Frederick Baume | Death | Arthur Myers | ||
| Christchurch North | 1911 | 17 August | Tommy Taylor | Death | Leonard Isitt | ||