Background:The present study aimed to clarify the current use and outcomes of coronary artery bypass grafting (CABG) for acute coronary syndrome (ACS) based on the Japan Adult Cardiovascular Surgery Database (JACVSD) in stratified risk categories, and also to provide guidance on selection of optimal surgical strategies for ACS.Methods and Results:From January 2008 through December 2012, 7,867 isolated CABG procedures for ACS were identifiedfrom the JACVSD. Patients were stratified into 3 subgroups (<2%, 2–9.9%, ≥10%) according to preoperative risk estimations based on this database. Off- and on-pump CABG surgical outcomes were evaluated in each subgroup. Off-pump CABG (OPCAB) was the predominant surgical strategy in all subgroups. The proportion of on-pump beating CABG increased in the higher-risk groups. Although average observed mortality rates were compatible with preoperative estimated risk in all subgroups, those after OPCAB were significantly lower in the medium (2–9.9%) risk group with lower incidence of major complications. In the low (<2%) and high (≥10%) risk groups, observed mortality rates did not show statistically significant differences between off- and on-pump CABG.Conclusions:In this study in Japan, OPCAB was mainly performed in patients with ACS, particularly those with estimated risk <10%, with lower mortality rates, whereas on-pump beating CABG was selected for higher-risk patients with ACS, with reasonable mortality rates.