[en] Colorectal cancer is really a public health problem. The authors review the literature about the environmental factors leading to colorectal cancer. Chemoprevention of colorectal cancer is also discussed, particularly by aspirin and non steroidal anti-inflammatory drugs. Development of specific cyclooxygenase-2 inhibitors constitutes a promising research's field. Secondary prevention by coloscopy and polypectomy must lead to a lower rate of colorectal cancer disease and improvement of mortality.