The long-term outcomes of 25 patients with childhood moyamoya disease (18 with the transient ischemic attack [TIA] type and seven with the non-TIA type), who were monitored to adulthood (older than 20 years of age), were evaluated in terms of residual clinical symptoms, intellectual development, and activities of daily living. Surgical treatment was performed in ten patients, encephaloduroarteriosynangiosis in nine, and superficial temporal artery to middle cerebral artery anastomosis plus encephalomyosynangiosis in one. Only seven with the TIA type (three surgically and four medically treated) demonstrated good activities of daily living without TIA or headache and normal IQ. Two patients with the TIA type and three with the non-TIA type demonstrated poor outcomes. Three of these patients with poor outcomes had renal artery stenosis. Surgery was effective in nine. Since the long-term outcomes of patients with childhood moyamoya disease are generally poor, surgical treatment is believed to be an effective procedure for preventing the progression of clinical symptoms.