Patients with ulcerative colitis are at greater risk of developing colorectal cancer than the general population. Prophylactic colectomy is the only certain method of avoiding this risk. To avoid indiscriminate surgery, efforts have focused on colonoscopic surveillance in order to select for prophylactic surgery only patients at ultra-high risk. However this policy has not always been proven to reduce mortality for colorectal cancer in these patients. Recently, there has been growing interest in chemoprevention using folate. Folate maintains the normal DNA methylation process and steady-state levels of DNA precursors. These properties indicate that folate has potential as chemopreventive agent.