The hemodynamic response to high-frequency ventilation was compared with conventional ventilation in six infants following cardiac surgery. While undergoing high-frequency ventilation, adequate gas exchange was maintained in all infants. High frequency ventilation allowed a reduction of peak ventilatory pressure at the airway opening by 19%, and peak tracheal pressure by 42%. No clinically important changes in heart rate, systemic and pulmonary arterial pressure, cardiac index, or systemic and pulmonary vascular resistance were noted when high-frequency ventilation was compared with conventional ventilation.