In 1975 in one of the major industrial districts of Budapest some longitudinal epidemiological examinations were carried out with the aim of, among others, determination of connection between environmental injuries and lung cancer incidence in connection with determination of lung cancer risk groups. Between 1975-1989 out of the environmental injuries the most important was the radioactive contamination observed due to the atomic power station catastrophe in Chernobil (1986). In 1987 the incidence of lung cancer increased. The increase was significant among the 50-69-year-old women, and expressly among the heavy smokers. In 1987, especially among women, but also in both sexes, the ratio among the major cell types of lung cancer shifted towards micro-cellular ones. In 1988 and 1989 lung cancer incidence has decreased. In view of the above a hypothesis was raised: patients who have previously suffered immunobiological hurt, could not prevent the increased radioactive burden and got ill with lung cancer earlier, than it should have been happened without this increased burden. For clarification this question further examinations are considered to be necessary.