Pouchitis occurs in 10-35% of patients in the first 10 years after pouch construction for ulcerative colitis. Pouchitis must be carefully defined and should not include patients with poor function or Crohn's disease. Most patients have only a single attack of pouchitis which rapidly resolves with metronidazole. Chronic pouchitis suggests some other abnormality of function which, if responsible for persistent poor function, may necessitate pouch excision.