Quantitation of peripheral circulating myeloma cell precursors, problems on serum beta 2-microglobulin value which is a prognostic factor in myeloma, and prognostic factors associated with long-term survival in our Japanese myeloma patients are described. Peripheral blood mononuclear cells were cultured in vitro in the presence of various recombinant cytokines and differentiated to plasma cells to quantify peripheral circulating myeloma cell precursors. It has speculated that the variation in the number of myeloma cell precursors in peripheral blood could be used as a parameter of the efficacy of chemotherapy in patients with myeloma. Serum beta 2-microglobulin value increased with age and under alpha-interferon therapy in myeloma, even if M protein decreased, suggesting that its value should be carefully monitored when evaluating the response to alpha-interferon and other chemotherapeutic agents. Of 1,119 Japanese patients with symptomatic myeloma who were newly diagnosed at 16 institutions of the Japan Myeloma Study Group between 1965 and 1981, 38 (3.4%) patients survived for more than 10 years. In comparison with 121 patients who died within 10 years in our institution, younger age, low and intermediate tumor mass, lower plasmacytosis, higher percentages of granulocytes and erythroblasts in bone marrow, and subtype classified as mature or intermediate were strongly correlated with long-term survival.