A 16-year-old boy, who had sudden left-sided hemiplegia, died two weeks following onset of symptoms. A right carotid angiogram showed stenosis at the termination of the internal carotid artery. The middle cerebral artery had a beaded appearance and some of its branches were occluded. A basal "moyamoya" syndrome and transdural anastomoses were present. At autopsy, multiple intracranial dissecting aneurysms were found. Arteries of the body displayed fibromuscular dysplasia (FMD). The relevance of dysplastic changes of intracranial arteries and the relationship to moyamoya syndrome are discussed.