Saint-Martin-l'Aiguillon (French pronunciation: [sɛ̃ maʁtɛ̃ lɛɡɥijɔ̃] ⓘ) is a commune in the Orne department in north-western France.

[3] The commune is made up of the following collection of villages and hamlets, La Grande Fichetière, Le Beauchêne, Pré de la Fosse and Saint-Martin-l'Aiguillon.

The commune is within the Normandie-Maine Regional Natural Park.

[5] Saint-Martin-l'Aiguillon along with another 70 communes is part of a 20,593 hectare, Natura 2000 conservation area, called the Haute vallée de l'Orne et affluents.

[6] The commune has one river, The Udon flowing through it, plus three streams, The Noes Morins, the Rouvray and the Rohan.