The most important factor contributing to morbidity following operation in this series of 55 cases of ulcerative colitis was sepsis, which occurred in 30 of the cases. There were four postoperative deaths in the series and three of these were attributable to sepsis. Adrenal steroid therapy for ulcerative colitis has in many cases produced remissions or allowed patients to be operated on in a chronic rather than an acute phase of their disease. However, prolonged use of steroids has also caused harmful procrastination of surgery in many instances. This procrastination can result in poorer candidates for surgery and resulting prolonged convalescence following surgery. Patients with acute ulcerative colitis not showing improvement following ten days to two weeks of steroid therapy should be operated on.