Pouchitis, a non-specific inflammation of the ileal reservoir, is the most frequent long-term complication after pouch surgery for ulcerative colitis. Incidence rates vary widely. The etiology is still unknown, but genetic susceptibility and fecal stasis with bacterial overgrowth seem to be important factors. A clinical diagnosis should be always confirmed by endoscopy and histology, and Pouchitis Disease Activity Index (PDAI), based on clinical symptoms, endoscopic appearance and histologic findings, represents an objective and reproducible scoring system for pouchitis. The treatment of pouchitis is largely empiric given the few controlled studies available. Antibiotics, especially metronidazole and ciprofloxacin, are the therapy of choice. Chronic pouchitis occurs in about 10-15% of patients; in these cases, further diagnostic tests should be performed to exclude alternative diagnoses. Highly concentrated probiotics (VSL#3) have been shown to be effective in preventing the onset and relapse of pouchitis.