Aneurysmal subarachnoid hemorrhage (aSAH) rapidly elevates intracranial pressure and disrupts intracerebral blood perfusion. As the objective evaluation of cerebral circulation is seldom performed due to the instability of the patient’s condition, we investigated the utility of measuring two indices of disturbed cerebral perfusion in the acute-stage of aSAH-regional cerebral blood flow (rCBF) and regional mean transit time (rMTT)-with computed tomography perfusion (CTP) to predict unfavorable outcomes of patients of aSAH. We enrolled 55 patients within the first 3 days of the onset of aSAH and used their modified Rankin Scale (mRS) scores to classify them into favorable (mRS, 0-2) and unfavorable (mRS, 3-6) outcome groups : 38 and 17 patients, respectively. The univariate analysis identified the following risk factors for unfavorable outcomes : age (p=0.004), World Federation of Neurological Society (WFNS) grade (p=0.005), presence of hydrocephalus (p=0.026) and delayed ischemic neurological deficit (p=0.005), and prolongation of rMTT of the cortex (rMTT-CTX ; p=0.014) and basal ganglia (rMTTBG ; p=0.003). The significance of higher WFNS grade (odds ratio [OR]=2.063, p=0.018), presence of delayed ischemic neurological deficit (OR=8.048, p=0.019), and rMTT-BG (OR=3.476, p=0.013) remained following multivariate analysis. Hence, CTP-derived parameters, especially rMTT, at admission can help to predict unfavorable outcomes in patients.