Aneurysms of the proximal anterior cerebral artery (A1) are rare. We investigated the clinical and angiographical characteristics, and treatment outcomes of A1 aneurysms by reviewing a total of 989 cases of ruptured or unruptured cerebral aneurysms treated with surgical clipping or coil embolization in our department and identified 12 cases of A1 aneurysms (1.2%), including 4 ruptured and 8 unruptured aneurysms. Three of the 4 patients with ruptured aneurysm were