Ulcerative colitis and regional ileitis may be accompanied by articular involvement as extraintestinal complications, and were observed in 11 and 4 patients respectively. The temporal connection between the intestinal diseases and the appearance of subsidence of these complications in the majority of the cases suggest an etiologic relationship, regardless of the fact that the etiology of the intestinal diseases has not yet been elucidated. The clinical picture and course as well as the laboratory findings indicate that the joint involvement in question differs from rheumatoid arthritis.