The efficacy and safety of high-dose chemotherapy with tandem autologous peripheral blood stem cell transplantation (auto-PBSCT) were evaluated in a multicenter clinical study of patients with advanced multiple myeloma. Eligible patients (n = 40) were consecutively enrolled in the phase I/II study and received 2-4 cycles of vincristine-adriamycin-dexamethasone regimen. The responding patients underwent PBSC harvesting following high-dose cyclophosphamide and filgrastim administration. The first auto-PBSCT (n = 32) following high-dose melphalan (200 mg/m(2)) was performed within 2 months of PBSC harvesting; the second auto-PBSCT (n = 28) was scheduled 3-6 months later. Treatment-related mortality was 2.5% (n = 1) throughout the protocol. Grade 4 nonhematologic toxicity occurred in 12.5 and 14.3% of the first and second auto-PBSCT patients, respectively. All but one patient (who died) achieved hematopoietic recovery. For the 28 patients completing the second auto-PBSCT, the results were favorable with a response rate of 65% (complete response rate = 27.5%, n = 11); the five-year progression-free survival and overall survival were 20.3 and 66.5%, respectively. In conclusion, high-dose chemotherapy with tandem auto-PBSCT is feasible and safe with a favorable response rate in treating advanced multiple myeloma in Japan.