The very varied pathology which underlies peritonitis caused by colonic diverticular disease makes the comparison of various methods of treatment very difficult. The best results are probably achieved by removal of the affected part of the colon from the abdomen as soon as possible. Really aggressive medical treatment is an essential accompaniment to any form of surgery. A two-stoma or Hartmann procedure is generally the safest form of resection. Immediate anastomosis has no particular advantage since it should always be accompanied by a proximal diverting colostomy, making a second operation necessary in any case. In desperate cases proximal colostomy may be the only possible procedure and can be life-saving. The advantage of a skin-bridge colostomy is stressed.In cases of haemorrhage the source of bleeding is usually impossible to locate. Conservative treatment is successful in most cases, but if there is no alternative to surgery subtotal colectomy with ileorectal anastomosis is the treatment of choice.