 The aim of this multicenter randomised trial in previously untreated patients with multiple myelome stage II, III DSis to assess the optimal timing of a second autologous stem-cell transplant.After a first-line therapy with thalidomide-dexamethasone followed by a PBSC collection, patients are randomly assigned to receive two autologous PBSC transplants arm Aor one autologous PBSC transplant followed by a consolidation therapy with thalidomide-dexamethasone arm B. Patients included in the arm B will receive a second transplant in case of disease progression on consolidation therapy, or in case of relapse in responders. 