From August 1979 through August 1991, 91 patients were supported with centrifugal mechanical ventricular assist. Major indications for its use were postcardiotomy ventricular failure (79) or as a bridge to cardiac transplantation (12). In postcardiotomy use (0.2% of all cardiac procedures), there were 54 male (68.4%) and 25 female patients (31.6%) with a mean age of 54.8 years and a mean duration of use of 3.56 days (range, 1 hour to 19 days). Forty-nine patients (62%) were successfully weaned, and 20 (25.3%) were hospital survivors. In 57 patients the device was inserted to wean from cardiopulmonary bypass, whereas in 22 it was employed later in the postoperative period because of low cardiac output or sudden arrest. Thirty-four (59.6%) of the 57 patients in the former group were weaned, and 15 (26.3%) were discharged, results similar to those in the latter group with 15 (68.2%) weaned and 5 (22.7%) discharged. Morbidity associated with use of centrifugal blood pumps included bleeding (87.3%; mean transfusion requirement, 53.2 units), renal failure (46.8%), cerebrovascular accident (12.7%), thromboembolism (12.7%), and hepatic insufficiency (12.7%). After a mean follow-up of 45.4 months (range, 2 to 142 months), 7 patients had died (35% late mortality), 1 patient is in functional class IV, and all others are in functional class I or II. Lower survival was associated with biventricular failure and renal failure but not with age or sex of the patient.