Transthoracic echocardiography (TTE) has been incorporated effectively into patient care in 90% of critically ill patients. However, despite its advantages in terms of its noninvasive nature, the quality of the images may be insufficient particularly in chest traumas and intrathoracic surgery. That is why transesophageal echocardiography (TEE) has replaced TTE in the intensive care unit (ICU), especially in patients with an endotracheal tube. Even now, there is a broad range of echo applications available to ICU physicians to enhance and improve their care of critically ill patients, with many new applications on their way. Echocardiography has a central role in critically ill patients as a diagnostic and hemodynamic monitoring tool. It has been suggested that echocardiography can change therapeutic management in about 25% of critically ill patients who are mechanically ventilated. TEE, albeit semi-invasive, is a completely safe procedure,with the incidence of esophageal perforation and mortality reported in 1 out of 5000 and in 1 out of 10,000 cases, correspondingly. Limited or highly focused bedside echocardiography in the ICU for differential diagnosis is very important and useful. As a general rule, whenever diagnostic information may change the management of the patient, and TTE cannot obtain sufficient data, TEE should be considered. The deployment of TTE and TEE is a category 1 indication in unstable patients with unexplained hemodynamic disturbances, suspected valve disease, or thromboembolic problems. There is a strong agreement regarding the use of TEE in persistent unexplained hypotension and hypoxemia.