The Trondheim region's (315 km2, population 154,000) emergency medical service (EMS) provides advanced cardiac life support (ACLS) with combined paramedic and physician response. This EMS system is commonly employed in Norway, yet no population based study of outcome in cardiac arrest has been published to date. This retrospective study reports incidence and outcome from every attempted out-of-hospital cardiopulmonary resuscitation (CPR) during 1990 through 1994 according to the Utstein template. Information on the patient's pre-morbid conditions and final outcome was obtained from hospital records. The incidence of cardiac arrest and CPR from all causes was 68 per 100,000 per year, with 83% primary cardiac aetiology. The median alarm to patient arrival interval for ambulance and emergency physician was 8 minutes and 11 minutes, respectively. The presenting rhythm was ventricular fibrillation or tachycardia in 51%, asystole in 34%, pulseless electrical activity in 8% and undetermined in 8%. Definite return of spontaneous circulation occurred in 211 patients (40%, 27 per 100,000 per year) and 57 patients (11%, 7.4 per 100,000 per year) survived to discharge. Most patients made a favourable cerebral outcome, although nine were severely disabled. This is the first population-based Norwegian study of outcome from out-of-hospital cardiac arrest in this combined paramedic/physician staffed EMS. Incidence, survival and neurological outcome are comparable with results obtained in other EMS systems.