From 1981 through 1985 intra-aortic balloon counterpulsation (IABP) was required by 90 patients on a total of 91 occasions. They included 85 (3.1%) of the 2751 patients undergoing open-heart surgery during that time. IABP was used preoperatively in 13 cases, to assist weaning from cardiopulmonary bypass in 64, postoperatively in nine, and without cardiac surgery in five cases. Complications arose from IABP in 24/90 patients (27%). The overall short-term survival rate following IABP was 61%, and the long-term (mean 23 months) rate was 51%. Early recovery of cardiac function was the main determinant of survival. Female sex, renal failure and postinfarction ventricular septal defect and mitral incompetence were over-represented among the nonsurvivors. IABP therefore is useful in reversible left ventricular dysfunction, whereas inadequate perfusion of vital organs with potential for failure of more than one organ system implies diminished likelihood of survival.