Background There is a significant relationship between calcification of the aortic arch (Arch) detected by chest X-ray examination and coronary artery disease (CAD), but the relationship between risk factors, CAD and aortic calcification detected during a mass screening program using a mobile helical computed tomography (CT) unit remains unknown. Methods and Results In total 2,623 subjects (1,347 men, and 1,276 women; mean age, 52.9±13.8) underwent an examination for lung cancer and tuberculosis using a mobile helical CT unit. The frequency of calcification was 19.6% in the Arch, 2.7% in the ascending aorta, and 10.1% in the descending aorta, values that were positively associated with age in both genders. Hypertension and smoking were significantly related to calcification of the thoracic aorta. There was a significant relationship between CAD and aortic calcification. The odds ratio of aortic calcification for patients with CAD increased as the number of calcified segments increased. Conclusions These results suggest that detection of calcification in the thoracic aorta during a mass chest screening using a mobile helical CT unit can be used to evaluate the risk of CAD. (Circ J 2004; 68: 538 - 541)