OUTLINE: This is a randomized, open label, multicenter study. Patients are stratified according to their beta 2 microglobulin (B2M) test at initial diagnosis (B2M no greater than 4 mg/L vs B2M greater than 4 mg/L vs unknown B2M). Patients are randomized to one of two treatment arms. Prior to stratification and randomization, patients receive a diagnostic dose of holmium Ho 166 DOTMP within days -31 to -10. Patients with adequate skeletal uptake of the diagnostic dose are randomized for therapy. Arm I: Patients receive holmium Ho 166 DOTMP IV over no more than 10 minutes within days -10 to -7 (at least 1 week and no more than 3 weeks after the diagnostic dose), melphalan IV over 20-30 minutes within days -3 to -1 (at least 24 hours prior to autologous peripheral blood stem cell (PBSC) transplantation), and autologous PBSC transplantation on day 0. Arm II: Patients receive melphalan and autologous PBSC transplantation as in arm I. Following transplantation, patients receive filgrastim (G-CSF) daily until blood counts recover. Patients are followed at 1 year, every 6 months for 3 years, and then annually thereafter.