False aneurysm of the intracranial arteries occurs infrequently as a complication of head injury and rarely as a consequence of other pathology. A case of false aneurysm of the supraclinoid internal carotid artery following minor intraoperative injury during clipping of a basilar-superior cerebellar aneurysm by the pterional approach is described. False aneurysm is a potential cause of recurrent intracranial hemorrhage after successful aneurysm clipping. Arterial bleeding which appears to come from the region of a branch origin should be viewed with concern even if it subsides spontaneously. © 1994, Canadian Neurological Sciences Federation. All rights reserved.