Although studies of patients with rheumatoid arthritis have found no increases in overall cancer rates, significant elevations in rates of lymphoma and myeloma have been reported, suggesting a causal relationship between autoimmune disorders and lymphoid malignancies. Nevertheless, only 22 cases of concomitant rheumatoid arthritis and multiple myeloma were identified during a retrospective national multicenter study carried out in France. Neither disease exhibited unusual features. In every case, rheumatoid arthritis preceded multiple myeloma. Monoclonal gammopathy preceded multiple myeloma in two patients, by 3 and 7 years respectively. No patient had amyloid arthritis. Analysis of data from the cancer registry of the Somme district in northern France did not suggest a significantly increased risk of multiple myeloma in rheumatoid arthritis patients (relative risk 2.3). Use of interferon alpha to treat myeloma has been reported to exacerbate concomitant autoimmune disorders.