Transesophageal echocardiography (TEE) is an efficient method for characterization of aortic atherosclerotic plaques (AAP). The aim of our study was to evaluate the feasibility and the additional contribution of three-dimensional (3D) TEE in the evaluation of AAPs in descending thoracic aorta. We studied 82 patients referred for TEE regardless of the indication. All patients underwent two-dimensional (2D) conventional acquisitions. A 3D TEE study was performed for all AAPs localized in the descending thoracic aorta. Thickness, degree of calcification, the presence of ulceration or mobile debris were compared for 2D and 3D modes. From 3D data, three types of AAPs were defined according to their morphological characteristics (surface and contours). Among 192 AAPs found on 2D acquisition, 189 (98.4 %) were also identified by 3D TEE. For AAP characterization, agreement was good between 2D TEE and 2D extracted from 3D with the multiplanar reconstruction mode: 83.6 % (k = 0.69) for thickness and 82.5 % (k = 0.72) for degree of calcification. All AAPs ulcerations (n = 13) and mobile debris (n = 3) seen in 2D were identified in 3D. 2D characteristics of the 3D AAPs’ morphological types were different: type I plaques were thin and rarely calcified; type III plaques were thicker and often calcified; and type II presented intermediate characteristics. There was overlap among groups and the 3D morphology could not be predicted from 2D data. 3D TEE is a feasible method for the analysis of AAPs. In addition to conventional characterization, 3D TEE provides a new morphological approach to AAPs.