A case of 66-years-old woman with mild renal failure due to deposition of K light chains on glomerular nodules, is reported. Monoclonal K light chains were found by immunofixation in serum and concentrated urine. Bone marrow examination showed a moderate increase of plasma cells, all stained for K light chains. Amyloid was not identified. No chemotherapy was started. Despite this, in the 15-months follow-up, renal function was preserved; no signs of myeloma, nor of extrarenal involvement were found. Careful follow-up is emphasized. The reason why light chains form amyloidoses or nodular deposits, like diabetic glomerulosclerosis of Kimmelstiel-Wilson, is briefly discussed, together with the differential diagnosis from other nephropathies.