Forty-seven patients, undergoing ileo-anal anastomosis for ulcerative colitis (42) or familial polyposis (5), were endoscopically examined after protective ileostomy or after restorative ileo-anal anastomosis. The neorectum and the ileum above were examined in all cases and multiple biopsies were taken. No symptoms of pouch inflammation were found in 41 subjects; 80.5% of these had non-macroscopic lesions and 19.5% had focal lesions such as congestion, petechiae, mucous hypersecretion (5), or single ulcers (3). None of these developed pouchitis. Pouchitis was observed in the other six subjects, who all underwent surgery for ulcerative colitis and developed 14 clinical episodes of pouchitis during the follow-up. In these cases the entire neorectum mucosa was always affected by the lesions which, in 50%, also extended to the ileum above. The most common endoscopic features (71.4%) were congestion, potechiae, oozing areas, mucous hypersecretion, and multiple superficial ulcers. In half the remaining cases (14.3%) the neorectum showed the features, described above, while the upper ileum was affected by deep round or irregular ulcers within normal mucosa; Crohn's disease was excluded in these cases. In the remaining 14.3%, pouchitis showed a pseudomembranous feature. In our experience, the endoscopic pattern of pouchitis is polymorphic. Although an ulcerative colitis-like feature prevails, pseudomembranous and Crohn's ileitis-like features may also be present.