Arteriosclerosis generally has various changes such as thickening and hypertrophy of the intima, fatty infiltration and calcium deposition in the arterial wall and atheroma, which lead to their loss of elasticity. Numerous experiments in animals have demonstrated with production of atheromatous lesions following the administration of large amount of lipoid substances such as cholesterol. However, many other factors such as hypertension, aging, heredity, maleness and arterial anatomy play an important role in the genesis of atherosclerosis. Atherosclerotic involvement of aorta usually produces no subjective symptoms unless involvement of the medium sized arteries arising from the aorta. In asymptomatic cases of atherosclerosis no method of antemortem diagnosis is available except roentgenographic detection of aortic calcification. Schilling, et al insisted that the lateral abdominal roentgenogram appeared to be not only useful in detecting large vessel atherosclerosis, but a so in the detection of asmptomatic aortic aneurysms, which are of more significance to the internist and surgeon. This study included reviews of 5166 chest roentgenograms (Thoracic group) and 1062 lateral roentgenograms of lumbar spine (Abdominal group) which were taken in Hanyang University Hospital during the period of May 1972 to April 1977. The ages of these cases were 40 or more. 1. About tow third of cases were fourties and fifties in both group. The sex distributions were almost equal. 2. The incidences of calcifications in the aortic arch and abdominal aorta were as below : Over all incidences of aortic calcifications were greater in females than in males in both groups. The incidences of both groups were almost equal in both sexes in the age group of 40-49, but much greater in females than in males in the age group over 60. 3. First degree calcifications of aortic arch were observed in 74.4%, second degree calcifications in 19.4%, and third degree calcifications in 4.2%. the third degree calcifications were only seen in the older age groups. 4. The incidence of aortic arch calcification was 16.9% in normal blood pressure group, and 22.8% to 31.0% in high blood pressure groups. 5. The mean serum cholesterol levels in normal persons were 182.6$pm$36.14$pm$ mg% in male, and 188.0$pm$41.44 mg% in female. The serum cholesterol level in the group of aortic arch calcification was slightly higher than that of group of no calcification, but the difference was not statistically significant. 6. The mean serum triglyceride levels in normal persons were 134.6$pm$450.1 mg% n male, and 141.3$pm$45.93 mg% in female. There was no difference in triglyceride levels of both groups of calcified and non-calcified aortic arch. 7. In the group of higher cardiothoracic ratio the incidence of aortic arch calcification was also high. 8. Discriminant functions were obtained for the differentiation of aortic arch calcification using 5 variables such as age, blood pressure, serum cholesterol, serum triglyceride, and cardiothoracic ratio. The formulae were as below: $alpha$1= -16.92191＋1.67682X1＋3.44059X2＋0.04873X3＋0.00676X4＋1.17398X5 $alpha$2=-11.09370＋0.94803X1＋3.36041X2＋0.04035X3＋0.00880X4＋1.04390X5 The percentages of likelihood were 75.7% in the group of aortic arch calcification and 76.1% in the group of no calcification.