Off-pump coronary artery bypass grafting (OPCAB) has become a more applicable procedure, even in patients with multi-vessel disease. However, the role of OPCAB for patients with acute coronary syndrome (ACS) requiring emergency revascularization has not been established yet. We reviewed our results of emergency coronary artery bypass grafting (CABG) for patients with ACS. Seventy-two patients with ACS who underwent emergency CABG were studied. Twenty-five underwent OPCAB and 47 on-pump CABG. OPCAB was mainly indicated for patients who were possibly at risk for cardiopulmonary bypass. When the coronary anatomy was suitable in younger or less risky patients, OPCAB was performed. Patients with multi-vessel disease or with a critical left main trunk lesion were not excluded from OPCAB. The mean number of grafted vessels was 2.6 per patient in the OPCAB group, and 3.8 per patient in the on-pump group (p<0.0001). However, none of the patients in either group required postoperative catheter intervention. Mean operative time was 195 minutes in the OPCAB group and 286 minutes in the on-pump group (p<0.0001). There were three postoperative deaths in the OPCAB group and four in the on-pump group. Multivariate logistic regression analysis revealed that preoperative cardiogenic shock was the only significant predictor for postoperative death (odds ratio, 7.33). The selection of the on-pump procedure or OPCAB did not correlate with operative death. Thus, we conclude that OPCAB can be performed safely and effectively in selected patients with ACS requiring emergency coronary revascularization.