Complications of the superficial temporal artery-middle cerebral artery(STA-MCA)bypass procedure include skin necrosis, MCA vessel wall injury, and thrombotic occlusion of the anastomotic site. First, deprivation of the STA per se induces ischemia of the skin flap. Skin incisions must be designed carefully to avoid isolating some areas from the blood supply. Secondly, the MCA walls can be extremely thin in moyamoya disease; therefore, the fragile vascular walls must be manipulated gently. The MCA walls should not be grasped directly by forceps. Thirdly, intraluminal thrombi can develop after the completion of the anastomosis. Heparin should be administered intravenously as soon as possible when intraluminal thrombi are detected, followed by aspirin loading via a nasogastric tube. Platelet(white)thrombi are fragile and easily disrupted with mechanical vibration. It is essential to treat them before they develop into a large, firm fibrin thrombus that completely occludes the anastomotic site, which would require suture cutting and surgical thrombus removal.