There is great potential for the use of plant-derived and natural dietary supplements in the fight to prevent onset or delay the progression of the carcinogenic processes. Pre-clinical, clinical and epidemiological evidence for their chemopreventive action is compelling, but, it is of increasing importance to determine more precisely the primary targets contributing to their efficacy, and conduct large randomized clinical trials before they are recommended for chemoprevention. These natural agents can also be very effectively used as an adjuvant agent along with standard anticancer agents.