In order to study the response of patients with multiple myeloma of the bones (MM) to various anti-cancer drugs (Melphalan M, Cyclophosphamide Cy, Nitrosourea NU, Vincristine V, Adriamycine A and Prednisone P), 70 MM received the following treatment : 1) Induction therapy : a) M and P or b) M and Cy and P ; 2) Levelling with partial or complete response : V Cy P (in case a) or V M Cy P (in case b) ; 3) Relapse : A and NU. The following results were obtained : 1) Only 42.6% of patients respond to induction therapy ; 2) Fewer than 10% of patients showing a response reach a second levelling with Vincristine ; 3) 50% of those not showing a response reach a levelling between --20 and --50 and have prolonged survival ; 4) Only 20% of non responders are improved by Cy P or A and NU. The median actuarial survival is 42 months. Among the responders two poor prognosis factors must be underlined : hypercalcemia and the speed of response.