To evaluate whether cerebral CT findings taken immediately after successful resuscitation from cardiopulmonary arrest (CPA) correlate with the outcome or not. We analyzed retrospectively brain sections with the Housfield unit (CT number). Between May 2001 and March 2004, 16 consecutive patients, who recovered from CPA, were included as subjects in this study. They satisfied all of the following criteria: (a) a helical multislice head CT was performed within 1 h of the return of the spontaneous circulation (ROSC); (b) patients died within 24 h after ROSC, and any patients with trauma or cerebral vascular disease were excluded. The subjects were divided into two groups; those with a cerebral performance category of 1-3 (GR group) and those with a cerebral performance category of 4-5 (VD group). There were no significant differences between the two groups except for age. The average ventricle size on the brain CT showed no significant difference between the two groups. The average CT number of the putamen and cerebral cortex, and the corticomedullary contrast in the GR group were higher than those in the VD group. Although the influence of age cannot be disregarded, the CT number of the putamen and cortex, and also the corticomedullary contrast correlated with outcome of hypoxic encephalopathy even when cerebral CT was performed within 1 h after ROSC following CPA.