The risk of cancer in IBD is real and is a cause of anxiety and concern among patients and practitioners. Current modalities for detecting dysplasia in IBD are crude and insensitive and subject to observer and sampling bias. This evidence-based review confirms a significant increased risk for colorectal cancer among patients with pancolonic UC and, to a lesser extent, in patients with left-sided disease. Risk increases with longer duration of disease; early age at diagnosis; coexisting PSC; and, perhaps, a family history of colorectal cancer. Physicians must pay greater attention to the manner in which they implement surveillance colonoscopies, including paying heed to the location and number of biopsy specimens required to maximize the benefit. With respect to CD, the evidence suggests that patients with extensive colonic involvement of long duration carry a similar risk of colorectal cancer to patients with UC and should be considered candidates for surveillance colonoscopy.