The experience of the senior author was 16 anterior choroidal artery aneurysms is reviewed. The anatomic variations of the origin of the anterior choroidal artery are discussed, and the danger of sacrificing the artery in aneurysm surgery is stressed. The surgical procedure upon these aneurysms has frequently been difficult, requiring careful microdissection. This was due to variations of the origin of the aneurysm in respect to the artery and their frequent contiguity.