Traumatic injuries still constitute one of the leading causes of death in all age groups. Emergency thoracotomy is a procedure carried out in patients presenting in extremis. The primary goals are the control of massive hemorrhage, the release of cardiac tamponade, the internal or open cardiac massage, the prevention or control of air embolism, the control of bronchopleural fistulae and the cross-clamping of descending aorta. Although the usefulness of prehospital emergency thoracotomy remains controversial and specific guidelines are lacking, when faced with no alternative, it can be a lifesaving procedure. A comprehensive search for relevant studies was performed from 1975 to the present. An algorithm is proposed to assist physicians in deciding when to perform on scene thoracotomy.