Intra-aortic balloon pump assist (IABP) was applied to 26 patients who could not be with-drawn from total cardiopulmonary bypass (CB) subsequent to elective surgery for multiple cardiac procedures. Eighty-eight per cent were able to separate from CB with IABP and were assisted for 36 to 168 hours. Seventeen were withdrawn from the balloon. Eleven (42%) are hospital survivors. Ten (38%) are alive at the time of this report. IABP was most effective when applied early to patients who had recognizable acute ischemic injury to the myocardium at the time of operation and/or presence of hypertrophied left ventricular myocardium with small chamber volume. Support in these conditions gave 50% survival. Poorest results were in patients with either extensive acute infarction or severe chronic irreversible myocardial damage.