Abstract： Background Outcomes in patients requiring coronary artery bypass graft (CABG) surgery have been improved with devices such as the intra-aortic balloon pump (IABP).Good coronary collateral circulation (CCC) has been shown to reduce mortality in patients with coronary artery disease (CAD).We aimed to investigate whether poor preoperative CCC grade is a predictor of in-hospital mortality in CABG surgery requiring IABP support.Methods Fifty-five consecutive patients who were undergoing isolated first time on-pump CABG surgery with IABP support were enrolled into this study and CCC of those patients was evaluated.Results Twenty-seven patients had poor CCC and 28 patients had good CCC.In-hospital mortality rate in poor CCC group was significantly higher than good CCC group (14 (50％) vs.4 (13％),P=0.013).Preoperative hemoglobin level (OR:0.752; 95％ CI,0.571-0.991,P=0.043),chronic obstructive pulmonary disease (OR:6.731; 95％ CI,1.159-39.085,P=0.034) and poor CCC grade (OR:5.750; 95％ CI,1.575-20.986,P=0.008) were associated with post-CABG in-hospital mortality.Poor CCC grade (OR:4.853; 95％ CI,1.124-20.952,P=0.034) and preoperative hemoglobin level (OR:0.624; 95％ CI,0.476-0.954,P=0.026) were independent predictors of in-hospital mortality after CABG.Conclusion Preoperative poor CCC and hemoglobin are predictors of in-hospital mortality after CABG with IABP support.