Among 97 specimens of ascending aorta from adults with clinical coronary disease, the prevalence of atherosclerotic plaques greater than 8 mm in diameter was 38%. The right side of the ascending aorta was more commonly involved than the left; the sites least commonly involved were the right-posterior, upper right-anterior, and lower posterior locations. Of specimens with plaques at the orifice of the innominate artery, 80% also had plaques in the ascending aorta, and 73% of specimens with plaques at the orifice of the left subclavian artery had plaques in the ascending aorta.