Up to date, only a small number of carcinomas arising from a chronic anorectal fistula have been described in medical literature, especially in patients without Chron’s disease. A 72-year-old man with a 6-year history of discharging perianal sinus without Crohn’s disease arrived at our institution. He had previously undergone three surgical procedures in other institutions for incision and drainage of recurrent perianal abscesses. Our therapeutical approach was to drain the two abscess cavities, perform a fistulectomy, and biopsy the fistula tissue. Anatomopathological examination of the specimen revealed a mucosecerrnig adenocarcinoma arising from the fistula tract. We decided to perform an abdominal perineal resection. The two-year oncological follow-up is negative. In conclusion, it is clear that the diagnosis of mucinous adenocarcinoma occurring in perianal fistula is difficult, particularly in patients without any risks or predisposing factors. Wide resection of the tumor with Miles’s procedure still represents the surgical treatment of choice and may provide a good long term outcome in localized disease