An analysis of results of operative treatment of 945 patients with peptic ulcers has been made. Among the factors responsible for bleeding the author names the elder age of the patients, bleeding in medical history, localization of the ulcer on the posterior wall of the duodenum, in the middle and upper thirds of the stomach on the lesser curvature, large size of the ulcer, penetration of the ulcer into the pancreas and liver. Perforations are potentially dangerous for ulcers of the frontal wall of the pyloroduodenal zone in patients of young and middle age with an aggressive course of the disease.