Randomised trials of coronary artery patency and mortality support the routine use of antithrombotic therapy in all patients with suspected acute myocardial infarction. At present, it is unclear whether antiplatelet therapy with aspirin alone will suffice or the addition of anticoagulation with either heparin or the newer specific thrombin inhibitor, hirudin, will confer a net benefit. The ongoing randomised trials, such as GUSTO-2 and TIMI-9, will provide relevant information on the use of aspirin plus heparin or aspirin plus hirudin in patients treated with thrombolytic therapy. The First American Study of Infarct Survival (ASIS-1) will provide data which are relevant to the large population of patients who, in the United States, do not receive thrombolytic therapy. When these data become available it will be possible for clinicians to make rational individual decisions and policy-makers to formulate guidelines concerning optimal antithrombotic therapy in myocardial infarction.