An emergency thoracotomy (ET) is a surgical procedure rarely practiced outside a hospital. However, it can be the only way to resuscitate a patient who has suffered cardiac arrest due to penetrating chest trauma. SAMUR-Protección Civil is a two-tier Emergency Medical Service of Madrid, with Advance Life Support teams led by Emergency Physicians, Emergency Nurses and Paramedics. Over the last 3 years, medical teams from SAMUR have performed ET in six cases, after a short period of cardiac arrest, restoring cardiac output in two cases, and one patient with a normal neurological outcome. The following SAMUR protocol describes these emergency situations and details the case of the patient who was treated and discharged from hospital without any repercussions.