Cardiac arrest occurs when organized cardiac contractility ceases and circulation stops. During cardiac arrest, electrical activity may be abnormal or absent, and the rhythm documented can be ventricular fibrillation, pulseless ventricular tachycardia, pulseless electrical activity, or asystole. It has been estimated that 300 000 sudden cardiac arrests occur each year in the United States, with 75% (225,000) occurring out-of-hospital and 25% (75,000) occurring in-hospital. A similar number occur in Europe each year. The 3-phase model of cardiac arrest, which proposes that a cardiac arrest progresses through distinct phases as time elapses, helps inform research and clinical care by providing a framework for improving outcomes from cardiac arrest. Early in an arrest, during the electrical phase, defibrillation is paramount. The circulatory phase begins after 4 to 5 minutes, and interventions to optimize circulation become of primary importance. When an arrest is prolonged, lasting for ≥10 minutes, the patient passes into the metabolic phase, in which significant metabolic derangements have accrued and start to dominate arrest physiology. If return of spontaneous circulation occurs during this phase, significant injury to diverse organs may have occurred, producing a critical illness known as post-cardiac arrest syndrome. The post-cardiac arrest syndrome has been recognized as a unique entity requiring unique therapies for successful management. Recent advances in cardiac arrest care include cardiocerebral resuscitation and the use of therapeutic hypothermia to treat comatose survivors of cardiac arrest.