The frequency, distribution, and severity of thoracic aortic plaques were evaluated by transesophageal echocardiography in 152 consecutive patients undergoing coronary arteriography. Coronary artery disease (CAD) was defined as > or = 50% stenosis of > or = 1 major branch. Atherosclerotic plaques were detected in the aorta in 90 of the 97 patients (93%) with CAD, but in only 12 of the 55 patients (22%) with normal coronary arteries. Atherosclerotic plaques in patients with CAD were found predominantly in the descending aorta (in 93%) and in the aortic arch (in 80%), whereas the ascending aorta was the least involved (in 37%). In the descending aorta, 58% of the plaques were complex (>3 mm thick, ulcerated, mobile, or calcified), and in the aortic arch, 40% of the plaques were so classified. Complex plaques were not found in the ascending aorta. The presence of an atherosclerotic plaque in the descending aorta had a sensitivity and a specificity for the prediction of CAD of 93% and 78%, respectively. In the ascending aorta, the sensitivity was lower (37%) but the specificity was higher (100%). The sensitivity of aortic plaques for the prediction of CAD was high in all age groups. Its specificity in subjects >63 years was lower than in younger subjects: 64% versus 90%, respectively. Multivariate logistic regression analysis showed that aortic plaques were a stronger predictor of CAD than were conventional risk factors.