Abstract During the last twenty years, 294 patients have been operated on at the Lahey Clinic for diverticulitis. The indications for surgery were perforation, obstruction, fistula, recurrent attacks of the disease, and occasionally the inability to rule out carcinoma. Of this group, 61.2 per cent had one stage resection. There were seven deaths and the over-all mortality was 2.38 per cent. The mortality for 180 patients who had primary one stage resection was 1.6 per cent. There were no deaths in the fifty-seven patients who had a three stage resection. This mortality is reasonable, but it could have been less. Much of the remaining morbidity associated with the surgical treatment of diverticulitis is caused not by the too frequent use of a three stage procedure but by complications occurring after one stage resection for patients with perforation or obstruction.