| Election Name: | 1990 Laurier—Sainte-Marie federal by-election |
| Country: | Canada |
| Type: | parliamentary |
| Ongoing: | no |
| Party Colour: | no |
| Party Name: | no |
| Previous Election: | 1988 Canadian federal election |
| Previous Year: | 1988 |
| Next Election: | 1993 Canadian federal election |
| Next Year: | 1993 |
| Seats For Election: | Seat of Laurier—Sainte-Marie |
| Candidate1: | Gilles Duceppe |
| Popular Vote1: | 16,818 |
| Percentage1: | 66.92% |
| Candidate2: | Denis Coderre |
| Popular Vote2: | 4,812 |
| Percentage2: | 19.15% |
| Swing2: | 19.9pp |
| Image3: | NDP |
| Candidate3: | Louise O'Neill |
| Popular Vote3: | 1,821 |
| Percentage3: | 7.25% |
| Swing3: | 14.4pp |
| MP | |
| Before Election: | Jean-Claude Malépart |
| Posttitle: | Elected MP |
| After Election: | Gilles Duceppe |
| Alliance1: | Bloc Québécois |
A by-election was held in the federal riding of Laurier—Sainte-Marie in Quebec on August 13, 1990, following the death of Liberal MP Jean-Claude Malépart.[1]
The by-election was held on the same day as another in Oshawa in Ontario. The seat was won by Independent candidate Gilles Duceppe, who later co-founded the Bloc Québécois in February 1991.[2] [3]