Résumé : Considering that in Brussels the first-aid ambulance team reaches the patient in cardiac arrest 10 min before the physician-manned ambulance, we instituted a feasibility study of early defibrillation by emergency medical technicians (EMTs). Three hundred EMTs received a 20-h automatic external defibrillation (AED) training course followed by a refresher course every 6 months. Of 316 cardiac arrests included in this study, asystole was encountered in 53% and ventricular fibrillation/ventricular tachycardia (VF/VT) in 33% of the cases on arrival of the EMTs. In the VFNT group, defibrillation was performed by EMTs with a Laerdal Heartstart 7-9 min before the medical team arrived. The overall cardiac arrest survival rate improved from 7% in 1989 to 19% in 1992. However, the long-term survival rate ( 14 105) of ventricular fibrillation remained low because of excessive delays in emergency medical service (EMS) access and in early ACLS. In conclusion, this work shows that in Brussels: (1) early defibrillation of cardiac arrest victims in VF is feasible by EMTs when a training and a follow-up program are implemented; (2) the weakest link of the chain of survival is the early EMS access, and the early ACLS; and (3) the AED program increases the interest and the efficacy of EMTs and medical teams in the management of cardiac arrests. © 1994.