10 young patients from 7 to 16 years of age with moyamoya disease were treated by temporal muscle graft (encephalo-myo-synangiosis: EMS) for the purpose of increasing extracranial and intracranial collateral circulation. Ischemic cerebrovascular symptoms and signs were encountered in all of them without intracranial hemorrhage. The patients were observed for 6–26 months after the first operation. Transient ischemic attacks disappeared in 4 out of 7 patients, and improved in frequency and duration in the remaining 3. Paresis of the limbs disappeared in 1 patient and improved in 2. In 2 patients, facial palsy disappeared and dysarthria improved as well. Ataxia disappeared in 2 patients, and involuntary movement of the extremities disappeared in 2. There were no ineffective cases clinically. In postoperative carotid angiography, the middle cerebral arteries were visualized clearly to the peripheral portion mainly via the thickened deep temporal arteries, and the abnormal vascular networks in the region of the basal ganglia reduced in size in most of patients. Improvements in intelligence quotient, electroencephalogram and cerebral blood flow were also obtained in several patients, respectively. EMS seemed to be an effective surgical treatment in young patients with moyamoya disease who suffered from cerebral ischemic symptoms.