Colitis-associated cancer, a type of colorectal cancers, is associated with inflammatory bowel disease, and it is possibly persistent inflammation that causes tissue dysplasia even carcinogensis. However, the molecular mechanisms remain to be elucidated. Recently colitis-associated cancer is attracting increasing attention due to its high mortality and difficulty in treatment. Some chemopreventive agents have been shown to reduce the risk of colitis-associated cancer. The present article reviews the recent advances of pathogenesis and chemoprevention of colitis-associated cancer.