Light chain disease is a type of multiple myeloma. Its clinical manifestation and bone marrow features are similar to those of other myelomas, but its prognosis is poorer than others. The authors have experienced a case of light chain disease by the electrophoresis and immunoelectrophoresis of the serum and urine and bone marrow biopsy with immunoperoxidase staining. This is a report of the case with clinical history and laboratory studies. A brief review of literature is added.