OBJECTIVE To determine whether combination chemotherapy with alternating cycles of vincristine, cyclophosphamide, melphalan, and prednisone (VCMP) and vincristine, carmustine (BCNU), Adriamycin (doxorubicin; Farmitalia, Carlo-Erba Laboratories, Spain), and prednisone (VBAP) is better than the standard melphalan-prednisone (MP) regimen in multiple myeloma (MM). METHODS From January 1985 to December 1989, 28 institutions of the Spanish Cooperative Group for Hematological Malignancies Treatment, Spanish Society of Hematology (PETHEMA) entered 487 eligible patients with symptomatic MM into the study. Patients were randomized to receive either MP or alternating courses of VCMP and VBAP. Logistic regression and the Cox proportional hazards models were used to assess the association between patients' characteristics and response rate and survival, respectively. RESULTS Among 449 patients who were assessable for response, the overall response rate to MP was 51.8% (31.5% objective response plus 20.3% partial response) as compared with 62.7% (45.2% objective response plus 17.5% partial response) to VCMP/VBAP (P = .025). Also, a significantly higher proportion of objective responses was observed with combination chemotherapy (45.2% v 31.5%; P = .004). The factors associated with an unfavorable response rate in the overall series were low platelet count, treatment with MP, high creatinine level and immunoglobulin, (IgG) monoclonal (M)-component. No significant differences were found when survival rates of both groups of patients were compared. However, patients with IgA myeloma treated with VCMP/VBAP survived significantly longer than those who received MP (median, 20.2 v 38.4 months; P < .005). CONCLUSIONS These results indicate that combination chemotherapy improves response rate in MM. However, this does not result in a significantly different survival rate, except for patients with IgA myeloma, who survive significantly longer with combination chemotherapy.