In the past three decades there has been a significant clinical shift in the performance of emergency department thoracotomy (EDT), from a nearly obligatory procedure before declaring any trauma patient to select patients undergoing EDT. The value of EDT in resuscitation of the patient in profound shock but not yet dead is unquestionable. Its indiscriminate use, however, renders it a low-yield and high-cost procedure. Overall analysis of the available literature indicates that the success of EDT approximates 35% in the patient arriving in shock with a penetrating cardiac wound, and 15% for all penetrating wounds. Conversely, patient outcome is relatively poor when EDT is done for blunt trauma; 2% survival in patients in shock and less than 1% survival with no vital signs. Patients undergoing CPR upon arrival to the emergency department should be stratified based upon injury and transport time to determine the utility of EDT. The optimal application of EDT requires a thorough understanding of its physiologic objectives, technical maneuvers, and the cardiovascular and metabolic consequences.