Bowen's disease of the anus and the perineum is undoubtedly a rare pathology. This is demonstrated by the fact that, while described by M. Bowen in 1912, only 112 cases have been reported in 1979. The differential diagnosis is more difficult than that of Bowen-like papulosis and Queyrat's erythroplasia. Ano-perineal Bowen's disease is, or may be, in a large number of cases, seen concomitantly with a primary ano-rectal or vaginal carcinoma, even if they were diagnosed after Bowen's disease.