Objective To investigate the effect of vitamin E on transcription activity of liver CYP450 1A1,CYP450 1A2,CYP450 1B1 genes in mice treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD).Methods Forty-five mice were divided into 5 groups,and the levels of TCDD and vitamin E were given at a dose of 0 and 0,100 and 0,100 and 20,100 and 100,and 100 ng/kg/d and 500 mg/kg/d,respectively.After 4 weeks,livers were taken to analyze the transcription activity of CYP450 1A1,CYP450 1A2 and CYP450 1B1 genes by real-time PCR method.Reaults There was an increasing tendency of liver CYP450 1A1,CYP450 1A2 mRNA levels in the mice treated with TCDD compared with those in the control group,while CYP450 1B1 mRNA level was significantly lower than that of the control group.When vitamin E was supplemented at a dose of 20 mg/kg,there was a decreasing tendency of CYP450 1A1 mRNA levels in comparison with the group treated with TCDD.The CYP450 1A1 mRNA levels increased with the increase of vitamin E dosage,and significantly increased at vitamin E 500 mg/kg compared with those in the group treated with TCDD.The CYP450 1A2 mRNA level was decreased with increase of vitamin E dosage,and was significantly lower at vitamin E 500 mg/kg than that of the group treated with TCDD.When vitamin E was supplemented in a dose of 500 mg/kg,there was an increasing tendency of CYP450 1B1 mRNA level compared to that in the group treated with TCDD. Conclusion These results suggested that TCDD can affect or partly affect transcription activity of liver CYP450 1A1,CYP450 1A2 and CYP450 1B1 genes in mice,and vitamin E can alleviate the effect of TCDD to a certain extent.