Numerous articles have been published about the events which occurred at Chernobyl and the radiological impact on the environment and the public. This article tries to find out which experience can be, should be or has already been gained from that accident. The fields which have been studied are: nuclear safety; radiation protection of rescue workers; medical treatment of overexposed persons; decontamination of agricultural land, buildings and cities; behaviour of radionuclides in ecosystems; effects of low doses on human beings.