Sudden death is a major problem in public health, affecting around 50 000 people a year in France. The prognosis for cardiac arrest is abysmal because for every minute lost the chances of survival diminish by 10%. The aim of this work was to prospectively evaluate the characteristics of cardiac arrest victims across an entire 6000 km? area, the Seine-et-Marne district, distinguished by the paradox of lying just outside the capital whilst actually being semi-rural, and to determine the current methods of dealing with this emergency. The DEFI 77 prospective epidemiological survey was carried out with the collaboration of the SAMU emergency medical service, the SDIS fire/ambulance service, the general hospitals and the Paris-Ile-de-France cardiological association. Between January 2001 and December 2005 there were 2001 cardiac arrests (mean age 68 +/- 20 years, 67% male) at home in 80% of cases. The arrest was in front of a witness in 72% of cases, but they performed resuscitation in only 14.3% of cases. The SAMU and SMUR emergency medical services attempted cardio-pulmonary resuscitation in 78% of cases. In 29% of cases, one or more external electric shocks were carried out, using a semi-automatic defibrillator 79% of the time. Only 11.5% of patients arrived at the emergency department alive, the overall hospital survival rate being less than 2%. Only eight patients subsequently underwent automatic defibrillator implantation. The results of this observational study are to a large extent explained by an extremely long delay (12 minutes) before help was called for, the delay between the call and the arrival of medical assistance (9.5 +/- 4 min), the low percentage of active witnesses, and the variability in management (invasive in particular). In conclusion, at the dawn of the third millennium the prognosis of cardiac arrest remains very poor and fully justifies educating the general public about calling for help early and about actions that can save lives, particularly external cardiac massage before the arrival of the emergency services, as well as the benefits of using automated external defibrillators.