The risk of colorectal cancer (CRC) and dysplasia in patients with inflammatory bowel disease (IBD) has been highly debated as risk estimates from different studies vary greatly. The present national Danish guideline on colonoscopy surveillance for dysplasia and colorectal cancer in patients with IBD is based on a thorough review of existing literature with particular focus on recent studies from Denmark revealing a lower risk of CRC than previously assumed. The overall risk of CRC in the Danish IBD population does not appear to be different from that of the background population; however, in some subgroups of patients the risk is increased. These subgroups of patients, who should be offered colonoscopy surveillance, include patients with ulcerative colitis having extensive disease and a long disease duration (10-13 years); early age at onset (less than 19 years of age) of ulcerative colitis; and patients with ulcerative colitis as well as Crohn's disease with a concomitant diagnosis of primary sclerosing cholangitis. A colonoscopy surveillance program is recommended in these subgroups with intervals ranging from every 3-6 months to every 5 years, using chromoendoscopy with targeted biopsies of the lesion and adjacent mucosa, instead of conventional colonoscopy with random biopsies. Preferably, the colonoscopy should be performed during clinical remission. If a lesion is detected the endoscopical resectability together with the pathology of the lesion and the adjacent mucosa determine how the lesion should be treated.