We investigated the present incidence of lung cancer and its distribution by histologic type in Nagasaki City using Nagasaki Tumor Registry data from the years 1973-1977. The risk of radiogenic lung cancer did not increase significantly in either sex. The difference in relative distribution by histologic type between the exposure and non-exposure groups was not significant. Further analyses should be carried out on the risk present for individuals who were young at the time the bomb was dropped and the effect of exposure distance on the incidence and histologic types of lung cancer in A-bomb survivors.