It is well known that blood pressure is elevated during acute stroke. Despite its importance for cerebral haemodynamics, cardiac output (CO) has been determined only in individual cases during acute stroke. We measured CO and blood pressure in patients with no history of heart disease who suffered from acute stroke (n = 30) and in a control group comparable with regard to age, gender and cardiac health (n = 30). CO, blood pressure and heart rate were significantly (P < 0.01) higher in the group of stroke patients than in the control group. There was a tendency for more time to have elapsed between the onset of symptoms and measurements, the higher the CO [b = 0.08 l/min per hour (-0.01; 0.17)]. Adjusted for age in a multiple regression model, the regression coefficient was significant (CO = 10.35 +0.094 x time -0.077 x age). The present study shows for the first time that patients with a healthy cardiovascular system who suffer from acute stroke have a higher CO than a group of comparable controls.