Cardiac arrest claims many lives too early. Cardiopulmonary resuscitation (CPR) is the treatment of choice in this dire situation where seconds count. Thus, a solid knowledge based on scientific data helps to guide the correct therapeutic armamentarium. Diagnostic workup, physical, electrical or pharmacological interventions are described and – where possible – classified according to published evidence. Special circumstances and ethical considerations are outlined and potentially harmful measures are summarized. Robust science should improve CPR for the majority of the patients.