We report a 10-year-old boy who has Fanconi's anemia and was admitted because of acute hemiplegia of the left side. Internal carotid arteriography disclosed a moyamoya cerebrovascular pattern on the right side. Although this condition may be acquired, it is suggested that in this case the moyamoya might pertain to the array of congenital malformations associated with Fanconi's anemia. Intracranial accidents occurring in Fanconi's anemia are generally ascribed to the bleeding tendency; however, the possibility of an underlying vascular anomaly should also be considered.