Saint-Marc-sur-Couesnon (French pronunciation: [sɛ̃ maʁk syʁ kwenɔ̃], literally Saint-Marc on Couesnon; Breton: Sant-Marzh-ar-C'houenon) is a former commune in the Ille-et-Vilaine department in Brittany in northwestern France.

[2] Saint-Marc-sur-Couesnon is located 35 km (22 mi) northeast of Rennes and 43 km (27 mi) south of Mont Saint-Michel.

The neighboring communes are Saint-Hilaire-des-Landes, Saint-Sauveur-des-Landes, La Chapelle-Saint-Aubert, Saint-Jean-sur-Couesnon, Mézières-sur-Couesnon, and Saint-Ouen-des-Alleux.

Inhabitants of Saint-Marc-sur-Couesnon are called médardais in French.

This Ille-et-Vilaine geographical article is a stub.