Transthoracic echocardiography may be of limited value for patients in intensive care units because of suboptimal patient positioning, surgical wounds, and mechanical ventilation. By contrast, transesophageal echocardiography provides a new window for cardiac imaging, even in critically ill patients. We report our indications based on findings comparing transesophageal and transthoracic echocardiography in 112 studies in intensive care units. The transesophageal approach diagnosed 131 significant findings, compared to only 95 (73%) found transthoracically. Transesophageal echocardiography was superior to the transthoracic approach in patients with significant (higher than 2+) mitral regurgitation, with improved detection in 10 (9%) cases (p less than 0.05). Transesophageal echocardiography also provided additional information in the evaluation of vegetations, diseases of the aorta, visualization of the left ventricle, intracardiac masses, intracardiac thrombi, and congenital heart disease. Transesophageal echocardiography provides a useful diagnostic tool for evaluation of critically ill patients.