Cavernous internal carotid artery (ICA)-anterior cerebral artery (ACA) anastomoses are unusual anomalies in which a duplicated A, segment of the ACA arises from the infraoptic ICA. The authors report on a 30-year-old woman who presented with subarachnoid hemorrhage from an anterior communicating artery (ACoA) aneurysm associated with an extremely rare variant of this anastomosis. The extra A, segment emerged from the ICA within the cavernous sinus rather than at or above the level of the ophthalmic artery. The presence of the anomalous vessel provided a straightforward endovascular approach to the ACoA and allowed the use of coil placement rather than surgical clipping to treat the aneurysm successfully.