Objective To study the possible mechanism of ginsenosides in regulating Th1/Th2 in rats with experimental autoimmune thyroiditis（EAT）.Methods Forty Wistar rats were randomized into the normal group

model group

low-dose group

middle-dose group

and high-dose group

with 8 in each.The EAT models were established by subcutaneously injecting porcine thyroglobulin（PTg）

Freund’s complete adjuvant（CFA） and incomplete Freund’s adjuvant（IFA）for 6 weeks in all groups except the normal group.The low-dose group

middle-dose group and high-dose group was gavaged with 14mg/kg

28mg/kg and 56mg/kg of ginsenosides respectively for 8 weeks.The normal group and model group were given equal amount of distilled water.The expressions of thyroglobulin antibody（TGAb）

thyroid peroxidase antibody（TPOAb）

interleukin-2（IL-2） and IL-4 were detected in all groups.Results Comparing with the normal group

the levels of TGAb

TPOAb and IL-2 were significantly increased but the IL-4 level was significantly decreased in the model group（P<0.01）.Comparing with the model group

the levels of TGAb and TPOAb were significantly decreased but the IL-4 level was significantly increased in the low-dose group and middle-dose group（P<0.05）.Conclusion Ginsenosides can reduce thyroid autoantibodies

and its mechanism may be relevant to reducing the expression of IL-2

increasing the expression of IL-4 and regulating the Th1/Th2 imbalance.