Objective: This is a retrospective study to find out the effectiveness of off–pump coronary artery bypass grafting (OPCAB) in critical left main disease. Method: A total of 354 patients were included in this study operated for critical left main coronary artery disease with severe triple /double vessel disease and operated by beating heart technique. Results: Early and late mortality in this group was .282% and 1.13% respectively. There was no conversion to on–pump bypass grafting. Mean ICU stay was 1.8 days. Low cardiac output rate was 1.41%, atrial fibrillation rate was 3.39%, both early and late cerebro–vascular accident rate was .282%, transient renal dysfunction occurred in.847%, chronic renal failure in 1.41%. There was no graft occlusion during follow–up. Conclusion: OPCAB in critical left main with severe coronary artery disease patients has similar, even better short and long term outcome, and we strongly recommend the use of OPCAB in critical left main disease