We report the case of a patient with steroid-resistant nephrotic syndrome which is caused by a renal amyloidosis. This clinical case is characterized by intensity of clinicals and biologicals abnormalities and by its uncommun cause. We also review current data on the nephrotic syndrome as well as on the systemic amyloidosis and to evoke the indications of the immunoglobulin free-light-chains quantification in the diagnostic approach.