A 24-year-old woman with a two-year history of inflammatory bowel disease, with no anal or perineal involvement, underwent a proctocolectomy and ileostomy. Pathologic evaluation of the specimen revealed Crohn's colitis and unsuspected perianal Bowen's disease. The patient is free of Crohn's and Bowen's disease 6.5 years later. The association of perianal Bowen's disease with Crohn's colitis is discussed.