Fourteen patients with diverticulitis who were clinically believed to require radiologic investigation form the basis of this report. An inflammatory mass (n = 10) or abscess (n = 2) were reliable findings on computed tomography. Other signs encountered were abnormal density of pericolic fat, thickening of colonic wall, and narrowing of the lumen of the colonic wall. Colovesical fistulas, all of which were suspected clinically, occurred in three patients. Computed tomography should be performed with administration of rectal contrast medium to demonstrate the origin of inflammation from the colon, assess pericolic extent, and confirm colovesical fistula.