This study was designed to investigate the effects of pyroligneous liquor on oxygen radicals and their scavenger enzymes in the liver of Cri/Bgi CD rats (7 rats per group).Male rats were fed a basic diet prepared in our Laboratory, PL-0 (Control), PL-1, PL-25, PL-50 and PL-75 groups were prepared to be 0%, 1%, 25%, 50% and 75% with distilled water using pyroligneous liquor (35% of Choa Co. Ltd.), and were administered orally for 8 wk.Superoxide radical contents in liver mitochondria and microsomes were significantly decreased to 12-14%, 11-15%, resp., in these PL-25 and PL-50 groups compared with the control group.Hydroxyl radical content in mitochondria and microsomes were markedly decreased to 12-20% and 17%, resp., in these PL-25 and PL-50% groups compared with the control group.Hydrogen peroxide content in mitochondria and microsomes were significantly decreased about 15-12% and 22-20% in liver of PL-25 and PL-50 groups compared with the control group.Mn-SOD and Cu/Zn-SOD activities in liver of PL-25 and PL-50 groups were remarkably increased to 15-25%, 11-16%, resp., compared with the control group.GPx activities in mitochondria and microsomes were significantly increased in the liver of PL-25 and PL-50 groups compared with the control group.CAT activities in mitochondria and cytosol were significantly increased to 12-14%, 15-27%, resp., in the liver of PL-25 and PL-50 groups compared with the control group.These results suggest that long term administration orally of 25 and 50% pyroligneous liquor may effectively inhibit the formation of oxygen free radicals, and also scavenger enzyme activities significantly increase through the administration orally.