OBJECTIVE The aim of this study was to evaluate the consequences of chronic pouchitis after restorative proctocolectomy for ulcerative colitis. METHODS Forty-two patients with chronic pouchitis underwent pouch endoscopy with biopsies after a median of 8.3 years of postoperative follow up. The pouchitis disease activity index (PDAI) was calculated. Morphological changes were recorded. Immunohistochemical analyses for cyclooxygenase 2 (COX-2), Ki-67 and p53 were performed, as was DNA flow cytometry. Endoscopy was also carried out in 10 patients without pouchitis and in nine healthy subjects. RESULTS In patients with chronic pouchitis, the PDAI was 6 (standard error of the mean ± 4). Eighteen (43%) patients used continuous medication. The PDAI correlated positively with villous atrophy (P < 0.05). None of the pouch biopsies showed dysplasia. COX-2 immunostaining was detected in 35 (83.3%) patients with chronic pouchitis, in five (50%) without pouchitis, but in none of the normal controls. COX-2 expression correlated with mucosal atrophy (P < 0.01). In 15 (35.7%) of 42 patients with chronic pouchitis, Ki-67 immunostaining was increased, but no increase was observed in either control group (P < 0.002). No p53 immunopositivity was found, and DNA flow cytometry was normal in all pouches. One of the patients developed adenocarcinoma at the anal anastomosis. CONCLUSIONS No dysplastic changes were detected during the first decade after surgery. Routine follow up of patients with chronic pouchitis with a hand-sewn anastomosis may not be necessary, although a small risk of cancer seems to remain at the anal anastomosis. The follow up should be focused on at-risk groups.