['Transesophageal echocardiography (TEE) is becoming a standard imaging tool during cardiac surgery as well as an important diagnostic tool in cardiology and in intensive care, resulting in an increasing demand for TEE training. To address the problem of limited time for learning during TEE studies, we have developed a novel online application that allows users to visualize each of the 20 standard diagnostic TEE views in conjunction with a three-dimensional (3D) heart model that can be rotated and "cut away" above the echo plane to reveal the internal cardiac structures. This study is an evaluation of the educational benefit of this application.', "The application was evaluated using a pre-test/post-test design assessing the improvement of subjects' test scores following three days of access to the application. The subjects were postgraduate fellows in anesthesia, cardiology, and cardiac surgery.", 'Ten subjects showed a significant increase (31%) in their test scores after an average of 130 min of access to the application over a three-day period (P < 0.001, effect size = 1.9). Using five-point Likert scales, the users indicated that the application was a useful addition to their training (4.7), they would recommend the application to their colleagues (4.9), and they found the application easy to use (4.4).'] Does an interactive online 3D model of the heart assist in learning standard transesophageal echocardiography views?