Anorectal manometry, coupled with measurement of rectal compliance, was carried out on 11 healthy subjects and 9 patients with ulcerative colitis. Resting pressure profile of the anorectum but basal rhythmic contraction of the anal canal was normal in most of the patients and rectoanal flex was positive in all. Rectal compliance was, however, significantly decreased in 7 of 9 patients. These results suggest that distensibility of the rectum may be decreased in cases of ulcerative colitis and that measurements of resting pressure profile, rectoanal reflex, and rectal compliance may be helpful in selecting patients suitable for elective surgery to preserve sphincter function.