A 33-year-old man was admitted to our hospital for suspected rectal tumor. Endoscopy showed a rectal mass not typical of carcinoma, and histologic evaluation of biopsy specimens revealed granulomatous inflammation. Venereal Disease Research Laboratories (VDRL) and Treponema pallidum hemagglutination (TPHA) tests became positive during hospitalization, and dark-field examination was positive for Treponemas, thus allowing the diagnosis of chancre of the rectum. The clinical and endoscopic features of this case are described.