By-elections to the 34th Canadian Parliament were held to fill vacancies in the House of Commons of Canada between the 1988 federal election and the 1993 federal election. The Progressive Conservative Party of Canada led a majority government for the entirety of the 34th Canadian Parliament, though their number did decrease from by-elections.
Sixteen seats became vacant during the life of the Parliament. Six of these vacancies were filled through by-elections.
| By-election | Date | Incumbent | Party | Winner | Party | Cause | Retained | ||
|---|---|---|---|---|---|---|---|---|---|
| Beauséjour | December 10, 1990 | Fernand Robichaud | Liberal | Jean Chrétien | Liberal | Resignation to provide a seat for Chrétien | Yes | ||
| York North | December 10, 1990 | Maurizio Bevilacqua | Liberal | Maurizio Bevilacqua | Liberal | Election declared void | Yes | ||
| Oshawa | August 13, 1990 | Ed Broadbent | New Democratic | Mike Breaugh | New Democratic | Resignation | Yes | ||
| Laurier—Sainte-Marie | August 13, 1990 | Jean-Claude Malépart | Liberal | Gilles Duceppe | Independent | Death | No | ||
| Chambly | February 12, 1990 | Richard Grisé | Progressive Conservative | Phil Edmonston | New Democratic | Resignation | No | ||
| Beaver River | March 13, 1989 | John Dahmer | Progressive Conservative | Deborah Grey | Reform | Death (cancer) | No | ||