The application of transesophageal echocardiography (TEE) in the perioperative setting has been expanding over the past decades. TEE has become increasingly important in the management of critically ill patients both in the operating room and in the intensive care unit (ICU). TEE is a semi-invasive imaging technique that provides a rapid, real-time, bedside assessment of cardiac function and morphology. It provides information about the anatomy of all cardiac structures and their functional status. A comprehensive exam evaluates both ventricles' morphology, dimensions, and wall motion. It can also detect any anatomical abnormalities and the presence of intracardiac masses or thrombi. Over the last few years, a large number of studies in different ICU and critical care settings and populations have demonstrated the feasibility of TEE in the management of hemodynamic instability. Hemodynamic parameters, such as volumes and pressures, can be obtained via TEE assessment of cardiac performance and may be helpful for diagnosis and treatment. Intraoperative TEE is actually considered an important diagnostic tool in patients scheduled for cardiac surgery as well as in high-risk patients undergoing non-cardiac surgery. All types of hemodynamic impairment can be quickly assessed via TEE, and the management of the echo data can define both the cause and the diagnosis.