The value of a high-fiber diet in preventing and treating colonic diverticula is firmly established. Although the diagnosis of diverticulosis is usually made with colonoscopy or barium enema examination, computed tomography has become the test of choice during acute diverticulitis, when the diagnosis cannot be confidently made clinically. Recently developed surgical principles for diverticulitis include radiographically directed drainage with delayed operation for peridiverticular abscess, resection of the site of disease in patients with general peritonitis, and primary anastomosis in most cases requiring urgent intervention. Diverticulosis accompanied by abdominal pain or irregular bowel habits is by itself rarely an indication for surgery. Diverticular bleeding usually resolves spontaneously, but persistent bleeding can usually be successfully treated with segmental colectomy after localization of the bleeding site with colonoscopy or arteriography.