In addition to mutagens and/or carcinogens a number of modulators of carcinogenesis are present in ourenvironment. Some of them are contained in our regular foods and therefore dietary factors play a role in thedevelopment of some types of cancers including colon cancer. Epidemiological studies have suggested that a diet richin fruits and vegetables is associated with reduced risk for a number of common cancers. There are still manyunknown constituents and/or factors in foods that could either enhance or reduce the possibility of developing cancer.Animal studies of experimental chemical carcinogenesis have indicated that several non-nutritive components infoods, belonging to different chemical groups, protect against certain types of cancers including colonic neoplasms.These chemicals are known as “chemopreventive agents”. Many of them are antioxidants and might suppresscarcinogenesis through: (I) inhibiting Phase I enzymes; (ii) induction of Phase II enzymes; (iii) scavenging DNAreactive agents; (iv) suppression of hyper-cell proliferation induced by carcinogens; and/or (v) inhibition of certainproperties of neoplastic cells. With the continuing increase in the incidence of colon cancer, there is an ever increasingneed to determine the most effective means for prevention and to understand the underlying mechanism(s). Previousstudies in our laboratory demonstrated protective effects of several naturally occurring products against rat colontumorigenesis. This article will introduce our recent studies in our search for chemopreventive effects of flavonoids(diosmin and hesperidin) and other phytochemicals in edible plants on rat colon carcinogenesis.