Recent clinical studies and an indication according to the severity degree provide new insight into the antithrombotic prevention with antiplatelet substances or oral anticoagulants in patients after myocardial infarction. After uncomplicated infarction 0.3-0.5 g acetylsalicylic acid are able to reduce both the reinfarction rate and mortality. Cardiogenic emboli in patients with nonrheumatic atrial fibrillation may be prevented by oral anticoagulants even in reduced dosage (INR 1.5-2.5). Oral anticoagulants in usual dosage may be applied in patients with a complicated course after infarction, i.e. with established intracardial thrombi, with aneurysm or myocardial akinesia, with dilated, large left ventricle or with atrial fibrillation. So far, controlled clinical studies comparing reduced oral anticoagulation and antiplatelet drugs to reduce the reinfarction rate and mortality do not exist. Meanwhile, new anticoagulant drugs, such as hirudins or synthetic thrombin inhibitors are under clinical investigation.