With an incidence of 50 - 70 resuscitations attempted per 100000 inhabitants and year Out-of-hospital cardiac arrest (OHCA) is one of the leading causes of death in adults in the developed world. Thus, cardiac arrest is a common emergency situation attended by emergency medical services (EMS). Due to the pathophysiology it is one of the most time-critical emergencies: after 3 - 5 minutes of cardiac arrest without resuscitation efforts the likelihood of neurological impairments is significantly increased once the patient survives the initial event. Therefore, the immediate start of basic life support (BLS) with high quality chest compressions is paramount. Advanced life support comprises defibrillation, if indicated, airway management, the application of selected drugs and the treatment of reversible causes. After return of spontaneous circulation (ROSC) a structured post-resuscitation care in EMS and in dedicated hospitals is essential to achieve the best neurological outcome for the patient. The universal resuscitation algorithm has to be adapted for special circumstances of OHCA (e. g. a traumatic cause, cardiac arrest in pregnancy, …).Georg Thieme Verlag KG Stuttgart · New York.