BACKGROUND Our purpose in this study is to evaluate the use of computed tomographic perfusion (CTP) as an imaging modality to assess revascularization after superficial temporal artery (STA) to middle cerebral artery (MCA) bypass in patients with moyamoya disease. METHODS We present a series of 5 patients (mean age, 35; range, 20-50) with moyamoya disease who underwent STA-MCA bypass for ischemic stroke or transient ischemic attack (TIA). Preoperatively, all patients were evaluated with CTP; all showed clinically significant hypoperfusion in the MCA territory. All surgeries were performed by the senior author (ASB) and there were no periprocedural complications. Postoperative CTPs were performed to assess improvement after the bypass. The postoperative CTP images clearly demonstrated patency of the bypass and restoration of flow, particularly in the MCA distribution. At follow-up (mean, 18 months), 3 patients continued to be asymptomatic, one patient's hemiparesis improved, and another patient's hemiparesis improved but remained aphasic (mean Glasgow Outcome Score, GOS = 4.5). All displayed a reduced risk of recurrent stroke; no MCA strokes were observed. CONCLUSIONS This study demonstrates that CTP, a more convenient and less expensive imaging test than other available options, can provide an assessment of cerebral blood flow after cerebral bypass that appears to correlate with postoperative clinical and angiographic findings. In addition, in this small series of moyamoya patients, STA-MCA bypass appeared to prevent recurrent TIAs and strokes.