#### Summary points Clopidogrel is well established in the treatment of acute coronary syndromes and is ubiquitous in cardiology practice. Landmark studies have established the importance of clopidogrel in the treatment of non-ST and ST elevation myocardial infarction and in percutaneous coronary intervention by reducing death, reinfarction, and adverse cardiac events. Knowledge of the benefits, risks, and duration of clopidogrel treatment is important for clinicians caring for patients presenting with and recovering from acute coronary syndromes. This review examines the recent key trials of clopidogrel in the treatment of acute coronary syndromes, as well as current cardiac guidelines from several professional societies. #### Sources and selection criteria We reviewed the most recent guidelines from the American College of Cardiology, National Institute for Health and Clinical Excellence, European Society of Cardiology, and American College of Chest Physicians on the use of clopidogrel in myocardial infarction. The landmark trials discussed in the above guidelines were retrieved for further review. We also searched for subsequent publications in this area by the key authors of the landmark trials. We searched Medline, Cochrane Library, and Embase using the terms “clopidogrel”, “thienopyridine”, “myocardial infarction”, “acute coronary syndrome”, “percutaneous coronary intervention”, “coronary stent”, and “coronary artery disease” for any additional landmark studies, …