Antioxidants-including C,E,BHA and BHT-have some chemical anticarcinogenic activities. They have been used to study mechanisms of chemical carcinogenesis. If BTH is mixed with a known carcinogen such as N-2-fluorenyl acetamide (FAA) or azoxymethane in the feed, the rate of tumor induction in rats is diminished. The mechanisms of antioxidants in chemical carcinogenesis are not well understood yet, but the relationship between chemical carcinogens and BTH has been intensively investigated.