Since 1977, IABP has been employed in 180 cases. We studied 94 adult patients who underwent open heart surgery and were treated with IABP procedure for the past 10 years, and investigated the following items, the timing of IABP initiation, preoperative left heart functions, aortic clamping time, period of IABP use, and mortality. Additional, P-V loop was measured during the operation. The following conclusions were drawn. When IABP was used preoperatively in cases with deteriorated cardiac functions, the incidence of in cases in which IABP was used during or after the operation. P-V loop is useful to obtain the detail of cardiac function which provides sufficient patient management during and after the operation, and could be useful for establishing the criteria of IABP use.