Proctitis and proctosigmoiditis may be distinct clinical entities. The lesions are restricted to the rectum or extend proximally to involve the sigmoid colon, respectively. Barium enema examination should be normal proximal to the rectum and sigmoid colon. Histology is used merely to confirm the disease process. We provide evidence drawn from a large epidemiological database that significantly more patients with proctitis than proctosigmoiditis followed over a mean period of 11 years became asymptomatic or had their diagnosis revised to a non-inflammatory bowel disease condition (p < 0.05). The 2 groups were well-matched for age, sex, duration of disease and received similar medical treatment. Future epidemiological studies and therapeutic trials should make a distinction between proctitis and proctosigmoiditis.