The general hemodynamic effects induced by a continuous intravenous infusion of syntheticbradykinin were studied in ten patients submitted to simultaneous right- and left-heart catheterization. A significant drop in systemic arterial pressure and in total peripheral resistance was observed, coincident with an increase of the cardiac output, heart rate, and stroke volume. There was no consistent change of the pulmonary arterial and left atrial pressures, but the pulmonary vascular resistance decreased significantly.