Atherosclerosis of the ascending aorta may be associated with a higher perioperative stroke risk in cardiac surgery. This study investigated the use of biplane transesophageal echocardiography (TEE) scanning of the entire thoracic aorta to predict the presence of plaque in the ascending aorta. Eighty-one patients (57 male, 24 female; aged 32-88 yr, mean age 64 yr) scheduled for elective cardiac surgery participated in an institutional review board-approved protocol. A comprehensive examination of the entire thoracic aorta in both the longitudinal and transverse planes was performed. After pericardiotomy, a sterilely draped 7-MHz probe was used to scan the entire ascending aorta in both long and short axis views. In both echocardiographic examinations, the presence and location of protruding plaques and intimal thickening > 3 mm were recorded. Using epiaortic (EPI) scanning as the 'gold standard,' the sensitivity, specificity, positive predictive value, and negative predictive value of TEE for detecting ascending aortic atherosclerosis were calculated. Fourteen (17%) of the 81 patients had significant atherosclerotic disease of the ascending aorta as diagnosed by EPI echocardiography. The sensitivity of TEE was 100%, the specificity was 60%, the positive predictive value was 34%, and the negative predictive value was 100%. These data show that, if the complete biplane TEE examination is negative for plaque, it is highly unlikely that there is significant plaque in the ascending aorta. If the TEE examination is positive for plaque, there is a 34% chance that there is significant disease of the ascending aorta, and EPI scanning should be considered. Thus, TEE is a very sensitive but only mildly specific method of determining whether ascending aortic atherosclerosis is present.