The Alagnon river starts in the Mounts of Cantal (Massif Central), near the "Puy Bataillouse" mountain, "commune" of Laveissière, at an altitude of about , in the Cantal department. First, it flows to the east, near the Super Lioran ski resort, and gets into a gorge and, then, into a valley near Murat. The river flows in general to the northeast and gets into deep gorges in Lempdes-sur-Allagnon.