Saint-Marc-le-Blanc (French pronunciation: [sɛ̃ maʁ lə blɑ̃]; Gallo: Saent-Mard-le-Blaunc, Breton: Sant-Mezar-Elvinieg) is a commune in the Ille-et-Vilaine department in Brittany in northwestern France.

On 1 January 2019, the former commune Baillé was merged into Saint-Marc-le-Blanc.

[3] Saint-Marc-le-Blanc is located 39 km (24 mi) northeast of Rennes and 33 km (21 mi) south of Mont Saint-Michel.

The adjacent communes are Saint-Brice-en-Coglès, Baillé, Le Tiercent, Chauvigné, and Tremblay.

Inhabitants of Saint-Marc-le-Blanc are called marcblaisiens in French.