Aims Aspirin combined with clopidogrel is the treatment of choice for acute coronary syndromes. Although the maintenance of aspirin until surgery does not affect postoperative bleeding after coronary artery bypass graft (CABG) surgery, the latter may be dramatically increased when clopidogrel is continued over a period of 5 days preoperatively. Methods and results: This prospective observational study will include 136 consecutive patients scheduled for first-time CABG. Postoperative bleeding and blood transfusion requirements will be compared (non inferiority)between patients pretreated during a period of 5 days prior surgery by either aspirin alone or combined with clopidogrel. Tranexamic acid will be systematically used in all these patients considered as high risk for bleeding.