Patients with longstanding extensive colitis, both ulcerative colitis and Crohn's colitis, have an increased risk of developing colorectal cancer. Because of this risk, colonoscopic surveillance for neoplasia is recommended by most authorities. Although there has been no randomised controlled trial to demonstrate surveillance effectiveness, there are several retrospective comparative studies, which suggest that surveillance reduces colorectal cancer mortality. Over the past decade there have been a number of developments in our understanding of colitis cancer. We have discovered that the severity of colorectal inflammation is an important risk factor, in addition to other known risk factors such as the extent and duration of colitis, primary sclerosing cholangitis and a family history of colorectal cancer. Endoscopic techniques have also improved and evidence now demonstrates that pancolonic chromoendoscopy yields significantly more intraepithelial neoplasia than random biopsies. Endoscopic resection of well-circumscribed lesions is now also recognised as being an appropriate strategy, potentially reducing the number of patients requiring colectomy. It is hoped that such developments will further improve the effectiveness of colitis surveillance.