A clinical course of complicated colonic diverticulosis in 91 patients is analysed. There were marked symptoms of the disease in 35 patients, complicated clinical course--in 38 patients, and mild symptoms--in 18 patients. The complicated clinical course occurred in 12 patients with acute diverticulitis, in 6 patients with perforation of the diverticulum, in 10 patients with bleeding, in 9 patients with the ileus, in 1 patient with the enteric fistula. 2 patients died after the surgery because of peritonitis. The difficulties of the differential diagnosis, the role of roentgenologic and endoscopic methods of examination are described. Surgical policy in complicated colonic diverticulosis is discussed.