Treatment of acute coronary syndrome has been based on the prevention of ischemic complications by means of antithrombotic therapy and invasive strategies. The desired reduction reached in the recurrence of ischemic events reveals its price, an increase in the occurrence of major bleeding. Initially tolerated as a benign complication, it is now shown to be an important predictor of mortality. Greater attention dedicated to the prognostic impact of bleeding is recent, motivated by the development of new antithrombotic agents. Detailed analysis of the risk factors for myocardial infarction or bleeding is an important issue and allows institution of individualized approach.