Patients who have had extensive colitis for more than 10 years are at increased risk for colorectal cancer. The risk may be greatest for those whose onset of illness is in childhood. Management options for patients at increased risk include prophylactic colectomy or endoscopic surveillance. The object of surveillance is prevention of cancer by detecting premalignant lesions that predispose to cancer. A less desirable objective is the diagnosis of cancer at an early curable stage. Patients must be well informed about their risk for cancer, the limitations of endoscopic surveillance, and the availability of surgical alternatives. Current endoscopic and pathologic techniques focus on the detection of dysplasia, but newer biomarkers may offer greater sensitivity and specificity in the future.