Either encephaloduroarteriosynangiosis (EDAS) or superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis combined with encephalomyosynangiosis (EMS) has been performed on most of the children with moyamoya disease in our department. EDAS alone was done in the parietal region of 13 sides in 10 patients, and STA-MCA anastomosis with EMS in the parietal region was done on 7 sides in 6 patients. The surgical results of these two different procedures were then compared. Postoperative collateral formation was observed on external carotid angiograms, and the improvement of clinical symptoms was monitored for 1 year after the bypass procedure. STA-MCA anastomosis with EMS was found to be superior to EDAS in both the development of collateral circulation (P less than 0.05) and postoperative clinical improvement (P less than 0.01). EDAS can be done easily and safely on small children with moyamoya disease, but STA-MCA anastomosis with EMS is considered to be more appropriate, whenever possible.