The designation "pseudomyeloma" is used to describe three patients who had a clinical picture that closely resembled multiple myeloma and was characterized by severe osteoporosis and a serum monoclonal paraprotein peak. The diagnosis of myeloma could not be made histologically, initially or after three, four, or ten years of observation. The protein abnormalities and the bone marrow picture remained stable. It is not known if this association has pathophysiologic importance or if it represents a chance phenomenon.