Carcinoma of the large bowel is one of the most common cancers in developed countries. Mortality-data in Austria (1975) indicate, that 87% of patients with colorectal cancer were over 60 years of age and 61,1% over 70 years of age. Some 80% of colorectal cancers and 50% of colonic adenomas give rise to occult bleeding and can be detected by means of a modified guaiac test. (Hemoccult). Establishment of strategies for insuring high compliance of participation in colon-cancer screening programs in the aged is therefore the most important goal for the future. Colonoscopy is emphasized as diagnostic tool of choice in asymptomatic patients at high risk or a positive hemoccult-test and in symptomatic patients. Air contrast barium enema should be used as complementary investigation. Digital palpation of the rectum as single examination in screening for large bowel cancer is insufficient and dangerous.