Optical colonoscopy (OC) is the gold standard for evaluating pathologies of the colon, including screening for colorectal cancer (CRC).The technological features of current colonoscopes have not progressed much in recent years except for improved image and video display.The technique requires intubation and insuffiation of the colon which are operator dependent.OC is an invasive procedure whose overall risk of complications is 0.3-2%.Computed tomographic colonography(CTC) has recently emerged as an alternative tool.This technology is attractive because it is simple to perform (for patients), it is probably very safe, although reports of colon perforation, usually in elderly patients and those with underlying colon disease, have emerged, and there is controversy about the risk of radiation exposure.Two large multicenter studies have demonstrated that CTC was significantly less sensitive than colonoscopy, whereas another demonstrated that CTC was more sensitive than colonoscopy for detecting lesions ≥ 10mm.