CT colonography is a CT examination focused on the detection of colonic polyps and masses. Its most common indications include incomplete optical colonoscopy and generally personal preference in symptomatic or frail patients. CT colonography has a diagnostic yield similar to optical colonoscopy. It is less demanding for the patient, has shorter examination times, lower rates of adverse effects (including bowel perforation) and allows limited evaluation of extracolonic structures. In 10-15 % of asymptomatic patients, optical colonoscopy is needed if either a colonic polyp or mass is detected. CT colonography requires bowel prior preparation, including laxatives and stool tagging with contrast material. Stool tagging can be completed for same-day CT colonography after an incomplete colonoscopy. Evaluation of extracolonic structures in CT colonography is limited, but CT colonography can be combined with other CT examinations (eg. CT of abdomen). C-RADS classification has been established for a more straightforward interpretation of findings on CT colonography. CT colonography and optical colonoscopy complement each other but do not compete.Key words: colonoscopy - colorectal carcinoma - CT colonography - polyp - screening - virtual colonoscopy.