Multiple myeloma is a blood disease that is often easy to diagnose, relying on a combination of an excessive medullary plasmacytosis, a serum and/or urinary monoclonal immunoglobulin and one or several signs of organ involvement (anemia, renal failure, bone lesions, hypercalcaemia, infections). The beta2m, serum albumin, and certain chromosomal anomalies of the malignant clone are the essential prognostic factors. Intensive treatment with auto-transplantation of stem cells of peripheral blood is a significant development from which patients less than or equal to 65 years of age have benefited. The diphosphonates are combined with chemotherapy in order to limit the effect on bones, and recombinant erythropoietin is used in certain patients. Above all, therapeutic progress has been made thanks to thalidomide, bortezomib and lenalidomide, even if the optimal utilisation of these molecules is still to be determined.