Couserans (; Gascon: Coserans ) is a small former province of France located in the Pyrenees mountains. Today Couserans makes up the western half of the Ariège département, around the towns of Saint-Girons and Saint-Lizier. A small part of Couserans is also in the extreme south of Haute-Garonne, just across the border from Ariège.
Couserans has a land area of 1,162 km² (449 sq. miles). At the 1999 census there were 21,260 inhabitants on the territory of the former province of Couserans, which means a density of only 18 inh. per km² (47 inh. per sq. mile), one of the lowest densities in western Europe. The only urban area is Saint-Girons (which includes Saint-Lizier), with 9,484 inhabitants in 1999 (44.6% of the whole population of Couserans).