Activities of hepatic cytosol enzymes involved in UDP-g1ucuronic acid synthesis as well as in glutathione reduction and conjugation systems were determined following administrations of butylated hydroxyanisole (approximately 5 mmol/kg body weight/day) and of equimolar intake doses of its structural anglogs. These compounds included the multi-functional group side chain compounds (t-butyl hydroquinone, 4-hydroxy-anisole, hydroquinone, benzoquinone) and the mono-functional side chain compounds (t-butyl benzene, anisole, phenol). They were administered to mice for 10 days either by mixing them in the diet or by oral intubations. Results showed that glutathione Stransferase activities were markedly increased by all tested compounds except for the t-butyl benzene. Activities of glutathione reductase and glucose 6-phosphate dehydrogenase were increased together on1y by BHA and t-butyl hydroguinone. UDP-glucose dehydrogenase and NADH:quinone reductase activities were significantly elevated by the multi-functional side chain compounds, but not by the mono-functional analogs. The relations between chemical structures of tested BHA analogs and elevations of the measured hepatic cytosol conjugation (detoxification) system enzyme activities for the metabolism and excretion of BHA analogs are discussed.