Original and reported data are reviewed with respect to the development, from childhood onwards, of coronary arterial atherosclerosis. The leading contribution of coronary arterial thrombosis to myocardial infarction is demonstrated, as is high incidence of excentric atherosclerotic patches in coronary arteries, which are prone to spasm in the presence of such patches; the course and complications of left ventricular and right atrial or right ventricular infarction are described. Data on "incomplete", stable and unstable myocardial infarction are presented.