After rats were treated with CC1₄, phenobarbital and artemisia messes-schmiaiana var viridis(artemisia), hepatic microsomal cytochrome P-450, cytochrome b₅ and lipid peroxidation were investigated. When vitamin A, C and E were added incubation medium in each group respectively, lipid peroxidation was observed. The results were as follows. 1) When administrated with CC1₄ in rats, the contents of total microsomal cytochrome P-450 and cytochrome b₅ were decreased by 58% and 36%, respectively. And lipid peroxidation was decreased to by 6%. 2) When administrated with phenobarbital and artemisia. in rats respectively, the contents of total microsomal cytochrome P-450 and cytochrome b₅ were increased by 25 to 135%. And lipid peroxidation was increased by 30 to 57%. 3) When administrated with CC1₄ and phenobarbital or artemisia. in rats, the contents of total microsomal cytochrome P-450 and cytochrome b₅ were increased by 8 to 35%. And lipid peroxidation was increased by 4 to 14%. 4) When vitamin A, C and E incubated in each group in each group in vitro, lipid peroxidation were decreased by 3 to 87%. And th higher concentrations of vitamin A, C and E were, the more lipid peroxidation was decreased. These results indicate that vitamin antioxidants can prevent lipid peroxidation in CC1₄, phenobarbital, CC1₄ with phenobarital. artemisia. and CC1₄ with artemisia.-pretreated rat liver microsomes.