The precancerous and early stages of colorectal carcinoma are, in the vast majority of cases, known and pathologically unequivocally defined. The precancerous and early stages of colorectal carcinoma can be detected by routine diagnostic measures (colonoscopy) with an adequate degree of reliability. A curative treatment of precursor and early stages of colorectal carcinoma is possible. As a rule, the procedure used is endoscopic polypectomy. A lowering of the incidence rates and mortality figures of large-bowel carcinoma through the routine detection and thoroughgoing endoscopic treatment of precursors of colorectal carcinoma would appear possible. The conclusion follows logically from the established points 1 to 3. The significance of polypectomy in the large bowel, which today is carried out routinely using a standardized technique, is to be seen in the prevention and early detection of colorectal carcinomas.