Intraoperative use of transesophageal echocardiography (TEE) to detect ischemia is more predictive of a postoperative myocardial infarction than is ECG, and two-dimensional (2-D) TEE has been shown to be more sensitive than ECG in detecting regional wall-motion abnormalities, which are highly suggestive of ischemia. More recent studies have demonstrated that postbypass TEE ischemia is predictive of an adverse outcome. Other potential diagnostic uses of TEE include evaluation and identification of intraoperative ventricular aneurysms and assessment of papillary muscle function. Intraoperative detection of thrombus and atrial myxoma has been significantly enhanced using 2-D TEE and, in the postoperative period, TEE is a more sensitive measure of pericardial tamponade than changes in hemodynamic variables. In cardiac surgery, contrast TEE has been reported to be useful in evaluating the adequacy of the delivery of cardioplegia as well as aiding in the detection of air emboli. The incorporation of Doppler into TEE probes now enhances the clinician's ability to diagnose and treat patients with valvular heart disease. The value of TEE must be weighed against cost-effectiveness and outcome as it becomes more widely used.