A case of myocardial infarction in a 23-year old male patient with Behçet's disease is reported. The infarction occurred 4 years after the onset of the disease, which had been marked by recurrent venous thrombosis. Coronary arteriography showed stenosis of the anterior interventricular artery and occlusion of the first diagonal artery; the other coronary vessels were normal. A search for vascular risk factors, including haemostasis, was undertaken, yielding only moderate cigarette-smoking. About 10 cases of myocardial infarction associated with Behçet's disease have been reported. They concerned young, usually male subjects. Infarction usually occurred late in the course of the disease, and vascular risk factors were seldom elicited. The leukocytoclastic vasculitis of Behçet's disease alone may be responsible for stenosis, thrombosis and false arterial aneurysms, as shown by anatomical studies. The physiopathological mechanisms involved (reduction of endothelial or systemic fibrinolytic activity, rise in fibrinogen and factor VIII) are still unclear; we believe that these abnormalities are inconstant. Behçet's disease may be regarded as a possible cause of myocardial infarction in young subjects.