We report the case of a keratoacanthoma of the anal margin in a 34 year-old man. Initial biopsies were negative. Diagnosis was made by histological examination of the surgical specimen. Nine cases of perianal keratoacanthoma have been previously reported in the literature. Our case is remarkable because of the young age of the patient. We discuss the differential diagnosis of anal keratoacanthoma that must be distinguished from well-differentiated squamous cell carcinoma.