Objective: The objective of this study was to determine whether hemodynamically stable, high-risk patients undergoing CABG benefit from preoperative use of an IABP support. Methods: Between Feb. 2000 and Oct. 2002, 60 high risk patients with CAD (presenting with two or more of these criteria: (LVEF) < 40%, LMS > 70%, REDO-CABG, unstable angina) underwent isolated CABG. These patients were randomized preoperatively into group I (received IABP 1—2 h prior CPB) and group II (underwent operation without preoperative insertion of IABP). Cardiac performance, mortality, morbidity and postoperative length of stay were evaluated and compared between the two groups. Results: Hospital mortality was higher in group II 23.3% (7/30) vs. 10% (3/30) for group I (p<0.05). Postoperative LCO, ventricular arrhythemia and PMI were significantly higher in group II compared to group I. They were (66.6% vs 16.6%), (36.6% vs 16.6%) and (26.6 vs 10%) respectively. Group I had shorter ICU stay, it was (57.6+19.2 vs. 115+62.8h) compared to group II, also shorter hospital stay it was (15.2+3.6 days vs. 20.3+6.7 days). In group II, 36.6 (11/30) did not require an IABP support after cardiotomy (subgroup IIa) while 63.3% (19/30) required an IABP support either intraoperative (subgroup IIb) or postoperative (IIc). The mortality rate did not differ in subgroup IIa and IIb compared to group I it was 9% and 11% vs. 10% respectively. But subgroup IIc had the highest mortality rate among the patients of study it was 50% (5/10), also it had the highest postoperative length of stay. Conclusions: Most high-risk patients with CAD undergoing CABG will in need to IABP support. Appropriate timing of IABP use either preoperatively (prophylactic) or on (as needed) basis without delay accompanied with lower mortality, morbidity and postoperative length of stay, while delayed use of IABP (as a last resort) accompanied with higher mortality, morbidity and postoperative length of stay.