The aim of this study was to investigate whether brain dynamic computed tomography (CT) is useful in predicting clinical outcome. Thirty patients suffering from cerebral ischemia in the territory of the middle cerebral artery (MCA) underwent dynamic CT scanning within 6 hours of stroke onset. Regions of interest (ROIs) were placed in the bilateral MCA territories and three parameters, peak value (PV), time to peak (TP), and PV divided by TP, were calculated from time-density curves (TDCs) on ROIs. After conventional treatment using pharmacological agents, the 30-day clinical outcome was evaluated on the Glasgow outcome scale. To investigate the relationship between the disease-to-contralateral side ratio of each parameter's value and 30-day clinical outcome, TDCs were classified into the following four types; type 1, with TP ratio less than 1.1; type 2, with TP ratio ranging from 1.1 to 1.5 and PV/TP ratio more than 0.75; type 3, with TP ratio ranging from 1.1 to 1.5 and PV/TP ratio less than 0.75; and type 4, with TP ratio more than 1.5 and PV/TP ratio less than 0.3. Clinical outcome in patients with type 1 or 2 TDC was better than in patients with type 3 or 4 TDC (p < 0.01, Fisher's exact test). We can conclude that dynamic CT is a useful means for estimating the clinical prognosis of acute stroke patients after conventional treatment. Poor clinical outcome following conventional therapy is expected in patients with type 3 or 4 TDC in contrast to patients with type 1 or 2 TDC.