The patient is 32-year-old, male who had been administered sodium bicarbonate and a small dose of α-mercaptopropionylglycine under the diagnosis of cystinuria, but during the 8th year of treatment he developed nephrotic syndrome. He suffered a number of recurrences which were treated each time with steroid only, but complete remission of nephrotic syndrome was achieved with the combined administration of methylprednisolone pulse therapy and cyclophosphamide.