Comparative anatomical macroscopic study of two groups of 24 cases of recently fatal first myocardial infarction (anterior or inferior) confirmed certain classical notions: higher age in females (p less than 0.02), inferior necrosis less extensive (p less than 0.05), higher occurrence of rupture of the myocardium in the case or an anterior lesion, and less frequent rupture but more often involving the septum in the case of inferior infarction. Furthermore the study showed the virtually constant presence of an intracoronary thrombus responsible for the infarction, the wider extent of atherosclerotic lesions in the right coronary system, and, above all, a fairly direct opposition between stenotic lesions most often proximal, and affecting the single anterior trunk (75%), in the case of anterior infarction, whilst significant atherosclerotic occlusion of the anterior (87%) and left (67%) systems were seen in the case of inferior infarction due to complete occlusion of the right coronary artery. These anatomical findings indicate the need for routine coronary arteriography after inferior infarctions, the recurrence of chest pain being related not to changes "in sity" but rather to significant occlusion of another coronary system.