Six patients received mechanical support for a failing left ventricle after corrective cardiac operations. Despite intra-aortic balloon pumping and pharmacologic support, intractable failure persisted and cardiopulmonary bypass could not be withdrawn. The left ventricular assist device (LVAD) consists of a nonpulsatile centrifugal pump and two thromboresistant cannulas. Balloon counterpulsation added a pulsatile effect. LVAD support was continued for 72 to 168 hours and five patients were weaned from LVAD support. Two died of persistent low cardiac output within 3 days after pump removal, and a fourth died of multiple organ failure and pneumonia 8 weeks after LVAD removal. Autopsy studies in the first three patients showed myocardial necrosis greater than 50% of the left ventricular mass. Two patients survived after 72 and 74 hours of LVAD support. One patient is fully employed and active 27 months after a cardiac operation; the second is fully active 20 months after operation. Repeat cardiac catheterizations in both have shown all grafts patent and good ventricular function. These two long-term survivors justify the concept of LVAD support and its continued use in selected postoperative patients.