The purpose of this study was to evaluate cerebral blood flow and territory through superficial temporal artery (STA) to middle cerebral artery (MCA) bypass in patients with Moyamoya disease after direct revascularization surgery using territory arterial spin labeling (tASL) technique. ASL and tASL scan were performed before and after bypassing surgery. our study demonstrated some bypasses can effectively supply blood flow into the brain and others cannot. tASL technique can selectively demonstrate perfusion territory through STA to MCA bypass. Thus, provide information about patency of STA to MCA bypass.