Moyamoya disease is a chronic, occlusive cerebrovascular disease with unknown etiology characterized by bilateral steno-occlusive changes at the terminal portion of the internal carotid artery and an abnormal vascular network at the base of the brain. Recent advances in molecular biology and genetic research have provided better understanding of the pathophysiology of moyamoya disease, but surgical revascularization still remains the preferred treatment for this entity. The present study investigated the clinical course of 106 consecutive patients with moyamoya disease who underwent superficial temporal artery-middle cerebral artery anastomosis with indirect pial synangiosis in 150 hemispheres. The outcomes of surgery on the operated hemisphere were favorable, with no cerebrovascular event during the outpatient follow-up period (mean 58.4 months) in 89.3% (134/150). Two patients suffered hemorrhagic events on the operated hemisphere during the follow-up period (2/150, 1.33%), one of whom suffered deteriorated neurological status after hemorrhage. Despite the favorable long-term outcome, the incidence of temporary neurological deterioration due to cerebral hyperperfusion was 18.0% (27/150), but no patients suffered permanent neurological deterioration directly caused by hyperperfusion. In conclusion, direct/indirect revascularization surgery is a safe and effective treatment for moyamoya disease, although the issue of bleeding/re-bleeding remains to be solved. Postoperative cerebral hyperperfusion and peri-operative infarction are potential complications of this procedure, so we recommend intensive postoperative care and cerebral blood flow measurement in the acute stage, because the management of hyperperfusion is contradictory to that of ischemia.