BACKGROUND: Bortezomib and thalidomide have shown synergy with melphalan and dexamethasone. We used this 4-drug combination as conditioning before autologous hematopoietic cell infusions. PATIENTS AND METHODS: Twenty-six patients with advanced-stage myeloma were treated with melphalan 50 mg/m(2) and bortezomib 1.3 mg/m(2) on days -6 and -3 in association with thalidomide 200 mg and dexamethasone 20 mg on days -6 through -3, followed by hematopoietic cell support on day 0. RESULTS: Nonhematologic toxicities included pneumonia, febrile neutropenia, and peripheral neuropathy. All patients had undergone autologous transplantation at diagnosis, and 13 patients (50%) underwent an additional transplantation at relapse. Responses occurred in 17 of 26 patients (65%), including 1 complete remission, 3 near complete remissions (12%), and 2 very good partial remissions (8%). Response rate was higher than that induced by the previous line of treatment in 12 patients (46%). CONCLUSION: Melphalan/bortezomib/thalidomide/dexamethasone showed encouraging antimyeloma activity in patients with advanced-stage myeloma.