The nuclear accident at Chernobyl accounted for an acute radiation syndrome in 237 persons on the site. Triage was the initial problem and was carried out according to clinical and biological criteria; evaluating the doses received was based on these criteria. Thirty one persons died and only 1 survived a dose higher than 6 Gy. Skin radiation burns which were due to inadequate decontamination, greatly worsened prognosis. The results of 13 bone marrow transplantations were disappointing, with only 2 survivors. Some time after the accident, these severely irradiated patients are mainly suffering from psychosomatic disorders, in the USSR, some areas have been significantly contaminated and several measures were taken to mitigate the impact on population: evacuating 135,000 persons, distributing prophylactic iodine, establishing standards and controls on foodstuff. Radiation phobia syndrome which developed in many persons, is the only sanitary effect noticed up to now. Finally, in Europe, there was only an increase in induced abortions and this was totally unwarranted. If we consider the risk of radiation induced cancer, an effect might not be demonstrated.