From December 1979 to April 1984, 266 victims of cardiac arrest outside the hospital in the metropolitan area of Florence received advanced cardiopulmonary resuscitation by a system for medical emergencies. 69 patients (25.9%) were successfully resuscitated and 42 (15.7%) were discharged alive from hospital without any neurological damage. The time delay between the onset of the cardiac arrest and the cardio-pulmonary resuscitation, the cardiac rhythm present on arrival of rescue squad, the degree of congestive heart failure immediately before the cardiac arrest and the neurological deficit after resuscitation significatively influenced immediate and late outcome.