Mesna:is a new sulfur-containing medicine developed in recent years,can prevent the hemorrhagic cystitis and other urinary system epithelial toxicity during the chemotherapy with large dosage of ifosfamide or cyclophosphamide.Serve as protective agent for the urinary track,applied to clinical with ifosfamide and cyclophosphamide, enormously relieve the pain of patient.This medicine has filled the internal gap,in favor of tumour treatment,and bates the toxicity of antineoplastic medicine.Up till the present moment,there is not the same kind of this medicine.