• Because of a family history of neurologic problems and the documentation of three vascular lesions in one patient, we evaluated 18 members representing three family generations with magnetic resonance imaging. Of these, eight were normal, two had abnormalities probably not related to arteriovenous malformation, one scan was suboptimal, and the remaining eight had evidence of hemorrhagic lesions characteristic of arteriovenous malformation. Four of these patients had multiple lesions, and three patients with lesions had no neurologic symptoms. The findings suggest an autosomal dominant mode of inheritance in this unique case of familial cerebral arteriovenous malformation.