The increasing incidence of colorectal cancer has emphasized the need for tools for the detection of polyps at risk of cancer or detection of malignant tumors in a more favorable stage. So far, no general prognostic risk factors are known which enable the diagnosis of cancer on the basis of simple tests or clinical symptoms. We know, however, that the prevalence of cancer and adenomas is age-related, with the highest incidence between 65 and 80 years. This should enable us to perform endoscopic screening programs on selected age groups to detect the malignant lesions at an earlier stage or to prevent the development of malignancy by removal of large polyps. Such screening programs should be performed in a controlled manner, to verify the impact of endoscopy on the prognosis and incidence of colorectal cancer. Meanwhile, the endoscopic surveillance of polyp-bearing patients will have to be conducted in accordance with the calculated risk of malignancy. Our increasing knowledge of risk factors in adenomas has, so far, allowed us to perform endoscopic controls of these patients less frequently than 10 years ago. For the future we hope to be able to select the high-risk individuals and adenomas for treatment, which in turn will enable us to ignore the majority of adenomas, which will definitely not undergo malignant transformation.