Since 1958, there have been 12 cases of multiple myeloma in Nagasaki, and among them were 7 cases representing atomic bombing casualties, with 3 cases being with 2 km distance from the hypocenter. The age of onset was between 51 and 69 years, and the sex ratio was 8:4, it occurring mostly in males. Symptoms were predominantly low back pain and chest pain caused by the bone changes in 8 cases. Two cases complained of general malaise and palpitation which resulted from anemia. One developed persistent epistaris, and another complained of diplopia caused by the paralysis of the oculomotor nerve. Peripheral blood in all cases showed anemia, 9 with hyperchromic and 3 with normochromic or hypochromic anemia. Low platelet counts were seen in 3 cases. All showed leukopenia. All cases showed typical ..gamma..-globulin change with a myeloma peak, and in 4 cases showed an increase of ..beta..-globulin. Bence-Jones proteinuria was present in 5 cases. Average course was 1 year 4 months. Among complications, myeloma nephrosis, aplastic anemia, and pneumonia were the most important ones.