We investigated the effect of age upon coronary atherosclerosis in eldery patients based on 2, 780 consecutive autopsies. Twenty-two hundred and fifteen patients who had no myocardial infarction on postmortem examination were classified as group A. The other 565 patients who had myocardial infarction were classified as group B. The coronary arteries were cross sectioned at 5mm interval, and the coronary stenotic index was defined as the sum of the highest stenotic scores in each major coronary artery; 0: without stenosis, 1: coronary atherosclerosis without stenosis, 2:25% narrowing of cross sectional area, 3:50%, 4:75%, 5: pinhole or complete occlusion. According to the number of 75% or greater narrowing of major coronary arteries, 0, 1, 2, and 3 vessel disease was defined.The overall incidence of myocardial infarction was 20.3%; the incidence increased above the age of 70. In group A, the coronary stenotic index was relativety low in comparison with group B and increased with age. The mean±SD of coronary stenotic index was 6.3±3.8 in sixties, 7.0±3.6 in seventies, 7.6±3.3 in eighties, and 7.8±3.1 in nineties (p<0.01, between each decades except nineties). However, in group B, the coronary stenotic index remained at the same level; 10.9±3.6 in sixties, 11.1±3.1 in seventies, 10.8±3.1 in eighties, and 10.6±3.3 in nineties. The mean coronary stenotic index increased with the size of myocardial infarction, 12.0 in large size, 10.8 in middle size, and 9.3 in small size infarction. However, no agewise increase of coronary stenotic index was observed within each infarction size. In group A, the incidence of 0 vessel disease was 69.4% in sixties, and it decreased with advancing of ages until 58.7% in nineties. In group B, the overall incidence of 0 vessel disease was 17.2%, and it remained at the same level with advancing of ages. The progression of low grade coronary atherosclerosis with advancing of ages in group A may imply physiological aging process. On the other hand, in group B, high grade coronary atherosclerosis which was independent of the age may imply pathological process and may have consisted the direct cause of death.