Many aspects of coronary artery disease in young people are not completely understood. Our study concerns a series of 100 patients < 45 years with acute coronary artery disease. Sixty patients survived and 40 died suddenly. All subjects have been divided into four groups: Group I includes 20 deceased patients with anatomic features of acute myocardial infarction. Group II includes 20 subjects dead without features of acute myocardial infarction. Group III includes 30 patients surviving the first acute myocardial infarction. Group IV includes 30 patients surviving unstable angina. The coronary arteries have been studied by anatomic dissection in Group I and II and with coronarography in Groups III and IV. The left main was only involved in Group I and II patients. Multivessel disease was more frequent in Group I and II, but the difference was not significant. These results underline that coronary artery disease with multivessel involvement is not rare in young patients. The rare occurrence of left main disease at coronary angiography could be the consequence of the natural preselection determined by sudden death.