Colorectal cancer, which is the third most frequent cancer and the cancer with the second highest mortality rate, frequently develops on a pre-existing adenomatous polyps whose slow growth and malignant degeneration can be identified and controlled by effective screening. Although most lesions can be detected and resected during optical colonoscopy (OC), the cost, risk and poor acceptance of this technique by the general population means that it is reserved for high-risk or very high-risk individuals. The fecal occult blood test (FOBT) (such as the Hemoccult^®) is proposed for intermediate-risk individuals between 50 and 75 years old. However, despite the improvements that have been made in this method, sensitivity is low, and although it is simple, it is too rarely used. CT colonography (virtual colonoscopy) is proposed in case of failure, additional risk factors or refusal of optical colonoscopy in high-risk patients or in the presence of a positive FOBT. It should also be proposed as an alternative to the FOBT test to patients who accept the constraints of this technique.