We aimed to evaluate the timing of preoperative intra-aortic balloon pump (IABP) placement and outcomes in patients undergoing off-pump coronary artery bypass grafting (OPCAB). Patients with prophylactic IABP placement before OPCAB presenting between January 1, 2010 and December 31, 2013 were included. Patients were categorized into two groups based on the timing of preoperative IABP placement: less than 2 h (Group A, n=223) and more than 2 h (Group B, n=94). According to the European System for Cardiac Operative Risk Evaluation (EuroSCORE), patients were divided into two subgroups: middle-low EuroSCORE (<6, Groups A1 and B1) and high EuroSCORE (6, Groups A2 and B2). Clinical data were compared between groups. Groups contained the following numbers of patients: Group A1, 163; Group A2, 60; Group B1, 60; and Group B2, 34. There was a significant difference in length of ICU and hospital stay between Group A and Group B, respectively (40.5 [22, 64] vs. 26.25 [18, 46.5] hours, P=0.006; 16 [11, 22] vs. 11 [8, 14] days, P=0.000). Duration of IABP support, ICU length of stay, hospital length of stay, and cost of hospitalization were significantly higher in Group A1 than in Group B1, respectively (73.69 +/- 44.12 vs. 64.03 +/- 40.93 h, P=0.013; 36 [20, 56.5] vs. 25.5 [17, 43.75] hours, P=0.035; 15(11,21) vs. 9(7.25, 12) days, P=0.000; 109.53(101.20, 131.1) vs. 102.7(95.94, 115.32) thousands CNY, P=0.009). The length of hospital stay was also significantly higher in Group A2 than in Group B2 (18(13, 26) vs. 13(11, 15) hours, P=0.000). Preoperative placement of IABP greater than 2 h prior to OPCAB is of benefit, especially in those with high EuroSCORE. The optimal time for prophylactic IABP placement requires further study.