It is widely recognized that perforation of the sigmoid colon leading to abscess formation or spreading peritonitis is a common complication of sigmoid diverticulitis. Much less common but occasionally reported is free perforation into the peritoneal cavity occurring soon after the onset of symptoms.1The two cases reported here differ, however, from any we have been able to find reported in the literature. Not only was perforation not preceded by symptoms or signs of diverticulitis, but at operation no inflamed diverticula were noted, although diverticula containing inspissated feces were palpated on either side of the perforation in both instances. We believe it is important to call attention to the possibility of spontaneous perforation in the presence of diverticulosis. In operating on patients with acute abdominal conditions, the surgeon at times discovers peritonitis without obvious cause. We are convinced from our experience with these two patients that the possibility of