The aim of the present randomized trial was to compare high-dose therapy (HDT) with continued conventional chemotherapy in patients with multiple myeloma (MM) who responded to the initial treatment. From May 1994 to October 1999, 216 patients (122 men/94 women; stage II or III; Eastern Cooperative Oncology Group [ECOG] score less than 3) entered the study. Initial chemotherapy consisted of 4 cycles of alternating vincristine, BCNU, melphalan, cyclophosphamide, prednisone/vincristine, BCNU, Adriamycin, dexamethasone (VBMCP/VBAD). Responding patients were randomly assigned to receive 8 additional cycles of VBMCP/VBAD, intensification with melphalan 200 mg/m2, or melphalan 140 mg/m2 plus 12 Gy fractionated total body irradiation (TBI). One-hundred sixty-four patients were randomly assigned, 83 to continued chemotherapy and 81 to HDT. The complete remission (CR) rate was significantly higher with HDT (30% vs 11%; P = .002). However, progression-free survival (PFS) was not significantly different between HDT and conventional therapy (median, 42 vs 33 months; P = not significant [NS]), and overall survival (OS) was similar in both groups (median, 61 vs 66 months). Finally, survival after relapse was identical in the 2 arms (15.9 vs 16.4 months). In conclusion, these results show that HDT intensification, when given to myeloma patients who have responded to the initial chemotherapy, significantly increases the CR rate but has no significant impact on PFS or OS.