A 6-year-old girl with an anal deformity had been complaining of pruritus around the anus. A small pit at 6 o'clock was diagnosed as an anal duplication. Fistulography showed a 0.5-cm-depth fistula without communication to the rectum. A 1.5-cm diameter presacral mass was shown on computed tomography. There was no sacral anomaly. At fistulectomy, the fistula contained mucous, yellow-white fluid. The base was enlarged, probably because of inflammation, but was resected without any invasion of the rectum. Histology showed squamous epithelium on the surface of the fistula and columnar epithelium and goblet cells in the base, which confirmed the diagnosis of an anal-canal duplication.