In order to observe the incidence of multiple myeloma in the population of Nagasaki City from 1973 to 1982, and to assess any influence caused by A-bomb exposure, 85 cases of myeloma have been collected and analysed. Informatively, 48 cases of this number were A-bomb survivors. Among the middle-aged cases, the crude incidence rates of myeloma in the exposed group were found to be higher than those in the non-exposed group. Further, the relative risk of myeloma was higher in A-bomb survivors and this tendency become more pronounced in the those who were within 2 km of the epicenter of the blast. The age-adjusted relative risk in male and female A-bomb survivors was 1.59 and 1.68 respectively, but no significant differences were noted.