Proctosigmoiditis, or distal colon ulcerative colitis, has been recognized as a clinical entity for over 50 years and considerable information has emerged from the study of the clinical course of patients with distal colon ulcerative colitis who are followed for a period of years. For most patients the condition is benign, although periods of exacerbation can occur between remissions, characterized by rectal bleeding. However, extension of the disease, development of cancer, and the requirement of surgery are all relatively unusual. It has recently been recognized that there are many other causes of proctitis than the idiopathic form, and this has raised important questions in differential diagnosis, particularly in the proctitis occurring in homosexual males. Proctitis, proctosigmoiditis, and distal colon ulceratice colitis and not Crohn's disease; conversely perianal fistulae and abscesses are rare in distal colon ulcerative colitis. Treatment with various forms of topical agents has often been satisfactory.