A 56-year-old female patient was clinically characterized by heavy proteinuria, anemia, hypertension, and no detectable monoclonal protein in serum or urine. She had a history of diabetes with retinopathy and hypertension. Histological investigation of renal biopsy specimens revealed nodular glomerulosclerosis. Light microscopic examination did not allow discrimination between diabetic glomerulosclerosis and monoclonal immunoglobulin deposition disease (MIDD). Immunofluorescent examination showed linear capillary wall and tubular basement membrane staining with kappa, and IgG staining. Electron-microscopic examination confirmed the amorphous material along the glomerular basement. Based on these findings, the diagnosis of light chain and heavy chain monoclonal immunoglobulin deposition disease (LHCDD) and diabetic nephropathy was made. At the present after the 7th course of melphalan and prednisolone treatment, her renal function and proteinuria have progressively improved.