Abstract:Objective：To explore the clinical and pathological characteristics of cancer deriving from chronic non-Crohn′s disease anal fistula. Methods：A retrospective study was made to analyze clinical and pathological data of 6 cases of chronic anal fistula from which cancer developed and were treated in our hospital from 1996 to 2005. Results：There were 5 males and 1 female averaging 55 years of age. The patients had chronic history of anal fistula for 15～30 years. The anal fistula carcinogenetic factor was chronic inflammation. The definitive diagnosis of the carcinogenesis depended on biopsy of the fistula wall and perianal mass. Metastasis to inguinal lymph nodes was found in 3 patients. All cases underwent abdomino-perineal radical resection(Miles operation )with adjuvant chemotherapy; three patients also had excision of inguinal lymph nodes. Three patients survived more than 5 years, two patients have survived for 3 years and 1 year respectively; 1 patient died of lung metastasis 1 year after operation later. Conclusions：Cancer deriving from chronic anal fistula develops slowly, is of relatively low malignancy but can be ignored easily in the early stage. Combined treatment in which the abdomino-perinal radical resection is the major method should be taken.