We assessed the ability of transesophageal echocardiography (TEE) to examine the entire length of the ascending aorta. TEE-derived data were compared with anatomic measurements and epiaortic scanning. There were 27 patients (19 male, 8 female; aged 67 ± 12 yr) studied during cardiac surgery. The surgeon measured the distance between the aortic anulus near the right coronary artery to the origin of the innominate artery (AV→IN) and to the level of the aortic cannulation site (AV→C). Independently, the ascending aorta was imaged by biplane TEE and the maximum length of aorta visualized was measured (TEE-MAX). Additionally, TEE was used to detect atheromas in the aorta and to visualize the aortic cannula. Epiaortic scanning was also performed in 14 patients. Direct measurement of the ascending aorta revealed a length of 8.9 ± 1.3 cm (mean ± SD) and the TEE-MAX was 7.4 ± 1.1 cm. The range of the difference between the two measurements was 0.2-4.5 cm. The aortic cannula was visualized only in 1 of 27 patients, and severe atherosclerotic plaques (>3 mm thick), not seen on TEE, were detected in five patients with epiaortic scanning. As much as 42% (4.5 cm of 10.7 cm) of the length of the ascending aorta was not visualized and potentially embolic plaques were not imaged by TEE. These findings suggest that even biplane TEE may have limited use in the precannulation assessment of the aorta for plaque and the detection of distal ascending aortic pathology.