Although there is no statistical proof of the efficacy of coumarin drugs in the therapy of acute myocardial infarction, the numbers of patients at risk from thromboembolism are sufficiently great and the favorable clinical and pathologic impressions are sufficiently strong that, conversely, the possibility of benefit cannot be excluded. This delicate balance is indeed a Hobson's Choice. In this therapeutic dilemma, we would interpret one acceptable course in regard to the use of anticoagulants among patients with acute myocardial infarction as follows: all patients with proved acute myocardial infarction should be treated with anticoagulants while hospitalized unless there are relative or absolute contraindications to the therapy or deficiencies in laboratory facilities. Patients with questionable infarcts should be treated with anticoagulants only until the diagnosis is established or rejected. If the latter occurs, the administration of the drug should be discontinued. When, in a patient suspected of having an acute myocardial infarction, there is reason to believe that the pain may be due to pericarditis, dissecting aneurysm, or gastrointestinal abnormalities, anticoagulant therapy should be withheld until this is resolved.