Objective:To observe the degree and mechanism of the hepatotoxicity induced by extract of saikosaponin in mice. Method: The time-toxicity relationship in mice were observed by giving the dosage of 36.075 g·kg-1 of extract of total saikosaponins and the changes of cytochrome P450(CYP450) and alenine transaminase(ALT)

aspartase aminotransferase(AST) were tested at different time points after being administered

and the morphological changes of hepatic tissue were observed by light microscope. The dosage-toxicit relationship in mice wereobserved by giving different dosages (36.075

21.650

12.975

7.925

4.675 g·kg-1 respectively) of extract of total saikosaponins and the corresponding treatment was performed 2 hours after administration in accordance with the method of time-toxicit relationship study. Result: The time-toxicity relationship study indicated that the level of CYP450 and ALT

AST in serum began to increase at 1 h after administration

and showed obvious differences compared with the control group

then it reached a peak level at 8

2 h and 2 h respectively. The dose-toxicity relationship study indicated that

compared with the control group

the level of CYP450 and ALT

AST in serum increased to different degrees at 2 h after administration

which showed a correlation with the dosage. Conclusion: The hepatotoxicity induced by the extract of saikosaponins is related to drug metabolism ability of the liver.