[en] The main hazard in the early phase after Chernobyl was radioiodine. Thyroid doses were esimated separately for (i) zones of strict control, (ii) most contaminated provinces (iii) the whole central European region of the USSR. Distinction was made between children under the age of 7 years at the time of the accident and the rest of the population. In the later phase the main concern is whole-body exposure to radiocaesium. Doses were calculated for the same areas and age groups as radioiodine. The following were considered: thyroid malignancies, leukaemia, other types of cancer, genetic defects and teratogenic anomalies. A stastistically significant excess over the spontaneous level is unlikely to be detectable for these effects, with the possible exception of thyroid disorders. The risk was greatly reduced by preventive measures, in particular lifetime doses have been restricted by establishment of a limit of 0.35 Sv. (author)