During a 4-year period, the authors examined 19 patients with Crohn's disease and associated ocular inflammation. Seven patients had uveitis, eight had episcleritis, and four had anterior scleritis. Large peripheral corneal infiltrates developed in two patients with scleritis. Increased bowel activity was closely related to the presence of acute episcleritis but not to uveitis or scleritis. To determine risk factors for the development of ocular inflammation, this group of 19 patients was compared with a group of 93 patients with Crohn's disease in whom ocular inflammation was not present. There were no demographic differences between the groups. Patients with colitis or ileocolitis were more likely to suffer from ocular inflammation (23.9%, 17 of 71), than patients with small bowel involvement alone (2.8%, 1 of 36) (P = 0.013). Those with arthritis or arthralgia had a higher incidence of ocular inflammation (29.4%, 15 of 51), than patients without joint involvement (6.6%, 4 of 61) (P = 0.003). These results suggest that the risk of developing ocular inflammation in Crohn's disease may be related to the site of bowel involvement and to the presence of arthritis.