We describe a 14-year-old Japanese girl with beta-thalassemia intermedia who developed moyamoya syndrome after splenectomy. This patient had compound heterozygous mutations of the beta-globin gene and received occasional transfusions. After splenectomy at 12 years of age, she transiently required partial exchange transfusions for leukoerythroblastosis but attained transfusion independence. Two years after the splenectomy, transient ischemic attacks occurred repeatedly with right hemiparesis or left paresthesia. Magnetic resonance imaging revealed bilateral stenosis of the internal carotid arteries and dilatation of the perforating branches with the formation of moyamoya vessels but not infarctions. The strict adherence to aspirin and dipyridamole has led to no stroke or progression of the vasculopathy for 8 years. Moyamoya disease has been reported in a patient with beta-thalassemia major. Cerebral vasculopathy can be a rare but grave consequence of the thromboembolic complications in beta-thalassemia major/intermedia. (J Child Neurol 2006;21:75-77).