Dietary habits in the civilised countries of the West with foods low in bulk and cellulose are blamed as causes of the increase in colon diverticulosis and the complicating diverticulitis in recent times. Of all sections of the colon, the sigmoid is most frequently involved, older patients above the 5th decade being principally affected. While uncomplicated diverticulosis of the colon usually remains symptomless, complicated diverticulitis often shows very uncharacteristic symptoms. For prophylaxis and the treatment of slight complaints, conservative treatment with administration of bulky foods (bran etc.) is indicated. Threatening hemorrhages and perforative peritonitis demand emergency operations. In closed abscess formation, internal or external fistulae and incipient scarring stenosis with imminent ileus, resection of the affected part of the intestine is indicated.