The angiographic and anatomical features of an anomalous communication between the intradural internal carotid artery and the anterior cerebral artery are described. Essential features of the anastomosis include an origin at, or close to, the origin of the ophthalmic artery, a course ventral to the ipsilateral optic nerve and anterior to the optic chiasm, and a termination near the anterior communicating artery. Although rare, the condition should be considered as an entity. The incidence of associated berry aneurysm and other congenital vascular anomalies is high.