Grand lac Saint François

For the lake in the Saint Lawrence River, see Lake Saint Francis (Canada).

Lac Saint-François
Location	Les Appalaches Regional County Municipality / Le Granit Regional County Municipality, Quebec
Coordinates	45°53′55″N 71°09′28″W
Primary outflows	Saint-François River
Basin countries	Canada
Surface area	51 km²

Lac Saint-François is a 51-square-kilometre (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.