Birth asphyxia often leads to left ventricular myocardial dysfunction. To assess the effect of myocardial dysfunction on cerebral perfusion, we evaluated cardiac output and cerebral blood flow velocity in the anterior cerebral and internal carotid arteries in 20 asphyxiated term newborn infants during the first 4 days of life using 2-dimensional/pulsed Doppler ultrasound. In 8 infants with myocardial dysfunction cardiac output was reduced on days 1 and 2 and within normal limits thereafter. In these infants changes in mean cerebral blood flow velocity and pulsatility index were passively related to changes in mean arterial pressure and cardiac output. In 12 infants without myocardial dysfunction a stable cerebral blood flow velocity pattern was found, which was unaffected by changes in mean arterial pressure. We conclude that infants presenting with a reduced cardiac output after deliveries associated with severe asphyxia may be at risk for additional ischemic or hemorrhagic cerebral damage because of lack of autoregulation.