Between January, 1973, and December, 1980, 33 patients were assigned at random to one of three different chemotherapy regimens: 12 patients received Melphalan only (M), 11 were treated with concurrent Melphalan and Prednisolone (MP), and 10 received Ifosfamide only (I). Comparative studies as to the response rates and survival times of these individuals were conducted and the results are summarized as follows: 1. The median age at the initiation of treatment was 63 years, ranging from 37 to 83 years. The 60-69 years age group was the largest. Fifteen (45.5 per cent) were male. 2. The incidences of IgG, IgA, and B-J protein only in M-protein type were 60.6%, 18.2%, and 21.2%, respectively. 3. In all regimens, the response rates as shown by marked diminishment of plasmacytoma and decrease of bone marrow plasmacytosis below 10 per cent were high and the calcification or disappearance of bone lytic lesions was demonstrated at low percentage. The frequency of over 50% reduction of the pretreatment value of M-protein level in M+MP and I therapy was 55.2% and 20.0%. 4. An analysis of patients, according to the clinical stage reported by Durie and Salmon, demonstrated that patients in stage I+II who received M+MP had a higher response rate and longer survival than those in stage III and that there was a significant difference between the survival of the stage I+II group and stage III (p=0.02). The results indicated that M+MP therapy was more effective in stage I+II than stage III.