Intra-aortic balloon pump [IABP] was applied to 12 patients between July, 1987, and September, 1990. The 12 patients included 8 who were assisted with IABP intraoperatively; 4 patients used IABP postoperatively. 8 patients could not be withdrawn from cardiopulmonary bypass [CPB], but 6 of them [75%] were able to separate from CPB with IABP. They all were withdrawn from the balloon. Four [50%] of them are hospital survivors, and alive at the time of this report. 4 additional patients were assisted with IABP, postoperatively. 2 of them [50Yo] were withdrawn from the balloon but died. The overall survival and balloon weaning rates are 33.3% [4/12] % 66.7% [8/12], respectively. IABP was most effective when applied early to patients who had transient and reversible injury to the myocardium.