Admission diagnosis of 100 patients with diverticular disease of the colon indicated that the clinical features of the disease is still relatively unknown. The most important cardinal symptoms are abdominal complaints, irregular stools and/or bleeding from the large intestine. These symptoms occur with about equql frequency in patients with diverticular disease, whether or not there was evidence of inflammatory complications. If there is clinically manifest diverticulum formation of the colon, the term "diverticular disease" seems appropriate, since transition between diverticulosis and diverticulitis is fluid. In addition to bleeding and attacks of diverticulitis, fistulae and gut narrowing with or without ileus are other complications. Mechanical small-intestinal ileus with involvement of the small intestine in the inflammatory diverticulitis mass was a feature of several of the authors' cases. Low-residue diet is contra-indicated because such food probably plays an important part in the aetiology and pathogenesis of diverticular disease.