Cephalocervical or intracranial fibromuscular dysplasia (FMD) can be identified by its characteristic angiographic appearance. Most of these lesions occur adjacent to the C1-2 interspace, characteristically sparing the origins and proximal segments of the major extracranial vessels. Approximately 65% of our patients had bilateral involvement of the cervical internal carotid arteries. Thirty percent were associated with one or more intracranial aneurysms. The vertebral arteries were involved in 10% of the cases. Twenty-four of 25 cases were associated with symptoms of either subarachnoid hemorrhage or focal cerebral ischemia.