There has been an explosion of new anticoagulants in recent years. new parenteral anticoagulants have been developed to overcome the limitations of heparin and low molecular weight heparin , whereas novel orally active anticoagulants have been designed to provide more streamlined therapy than vitamin K antagonists. Focusing on drugs in more advanced stages of clinical testing, this review identifies the molecular targets of new anticoagulants, describes the results of clinical trials, and provides perspective on the opportunities for new anticoagulants.