Therapeutic result and pitfalls in the surgical treatment of cerebrovascular moyamoya disease are evaluated. During the recent 15 years, 268 patients with moyamoya disease have been treated in our clinic. Among them, 238 patients showed ischemic symptoms. Superficial temporal artery to middle cerebral artery anastomoses combined with temporal muscle grafting (encephalo-myo-synangiosis) were performed for most of the cases. Complete remission and clinical improvement were obtained in 34.0% and 64.2% of the patients, respectively. Symptomatic aggravation due to ischemic complication followed the operation in five patients (1.9%). Normocapnic control during general anesthesia with sufficient hydration is essential to avoid perioperative ischemic complications. Omental graft was performed in 16 patients. In 13 patients, omental graft was performed for the progressing ischemia in the posterior cerebral artery or anterior cerebral artery distribution. In the other three patients, omental graft was used for marked brain atrophy.