An overlap of inflammatory bowel disease and diverticular disease has long been recognized. Crohn's disease and diverticulitis share clinical and radiologic features but usually differ in histopathologic findings. There is a suggestion, however, that even the characteristic pathology of Crohn's disease can be a secondary reaction to diverticulitis. It is possible, moreover, that the presence of Crohn's disease in association with diverticulosis predisposes to the development of diverticulitis. Finally, an apparently distinct form of segmental colitis associated with sigmoid diverticula has been described further contributing to the overlap of inflammatory bowel disease and diverticular disease.