The superior imaging capabilities of TEE have rapidly thrust this technique into the mainstream of noninvasive cardiology. However, the semi-invasive nature of this procedure requires specialized training on the part of the echocardiographer and adaptations of the traditional echocardiographic laboratory. These requirements will become even more evident as this technique is employed increasingly for interventional studies such as transesophageal atrial pacing and pharmacologic stress. TEE has proved efficacious and safe, even in critically ill patients, and its applications continue to expand. Following an article on anatomy, encompassing single and biplane orientation, the remainder of this monograph addresses the established as well as the emerging applications of TEE.