A 12-year-old boy with a history of "migraine" headache presented with an increasingly severe headache accompanied by emesis and unsteadiness. Evaluation revealed an acute cerebral hemorrhage with subsequent angiographic studies demonstrating multiple areas of segmental narrowing in both the anterior and posterior cerebral circulations. He was diagnosed with isolated angiitis of the central nervous system and high-dose steroid therapy was administered to which he responded for 6 months. Symptoms recurred and repeat angiography demonstrated persistent segmental narrowing. Pulse cyclophosphamide therapy was begun with resolution of symptoms and normalization of angiography following 6 treatments. Although rare in children, isolated angiitis of the central nervous system can occur in children and aggressive immunosuppression should be considered as the mode of therapy.