Abstract: Objective：To investigate the clonal origin of malignant cell in recurrence of urothelial carcinoma. Methods：The p53 gene mutations were evaluated by polymerase chain reaction single-strand conformation polymorphism（PCR-SSCP），and protein expressions were detected by immunohistochemistry in 30patients with urothelial neoplasms and their corresponding recurrented 80 pieces of tumor tissues.Mutations in p53 inferred on the basis of immunostaining.Results：The p53 protein expression of recurrented tumor in identical patient completely matched was seen in 63.6%，and mismatched 36.4%.The results indicated that two thirds of recurrented tumor are derived from the monoclonal cell，and one third is polyclonal.Conclusion：The most of relapsed urothelial tumors are origined from monoclonal cell，and small part from polyclone.