A new technique of circulatory support by total left ventricular bypass is presented. Ten large, conditioned dogs had total circulatory support for four hours with pulsatile flow. Since the right ventricle and lungs were not bypassed, no oxygenator was needed. The various physiologic parameters measured changed very little. The arterial and venous pressures, vascular resistance, and flow from the pump remained constant. Arterial pH, oxygen pressure (PO2), carbon dioxide pressure, and lactate, and the venous PO2 stayed within the normal range. Average hemolysis was only 14.5 mg/100 cc/hr and the urine output was 19 cc/hr. The technique was used successfully in one patient.