Colorectal cancer is a very important cause of death and disability throughout the world. In the future, it may be possible to reduce the risk of this disease through such measures as dietary modification or use of aspirin or other nonsteroidal anti-inflammatory drugs, but this remains to be proved. It may also be possible to detect persons at high risk or those with early lesions by using noninvasive studies, such as genetic tests or detection of trace markers in the stool, but these approaches either are not yet available or are not proved in clinical trials. However, through careful and systematic clinical history taking and appropriate screening studies, neoplasms can be detected early or in the precancerous stage. Mortality from colon cancer could be reduced dramatically by applying currently available methods as part of a health maintenance program. Fecal occult blood testing and flexible sigmoidoscopy must be integrated into practice routines in the same way that Pap smears and mammography have been accepted by physicians and patients as a way to save lives.