This review article on the surveillance of patients with ulcerative colitis provides an overview of the criteria for evaluating screening and surveillance programs and applies the criteria to the available evidence to determine the effectiveness of the surveillance of patients with ulcerative colitis. We examine the clinical outcomes associated with surveillance, the additional clinical time required to confirm the diagnosis of dysplasia and cancer, compliance with surveillance and follow-up, and the effectiveness of the individual components of a surveillance program, including colonoscopy and pathologist's interpretation. The disability associated with colectomy is considered, as are the cost and acceptability of surveillance programs. Patients with long-standing ulcerative colitis are at risk for developing colorectal cancer. Recommended surveillance colonoscopy should be supported. New endoscopic and histopathologic techniques to improve the identification of high-risk patients may enhance the effectiveness and cost-effectiveness of surveillance practices.