| Lac Saint-François | |
|---|---|
| Location | Les Appalaches Regional County Municipality / Le Granit Regional County Municipality, Quebec |
| Primary outflows | Saint-François River |
| Basin countries | Canada |
| Surface area | 51 km² |
Lac Saint-François is a 51 square kilometres (20 sq mi) body of water located southeast of the city of Thetford Mines, in southeastern Quebec. Much of the lake is surrounded by the Frontenac National Park. It is the source of the Saint-François River. There are six communities on the shores of the lake, the largest of which are Adstock, Saint-Joseph-de-Coleraine, and Lambton.