AIM: To study the antiviral effect of Chinese medicine jiaweisinisan (JWSNS) on hepatitis B virus (HBV)infection in transgenic mice (TGM).METHODS: Twenty two 6-8 wk old HBV TGM in the third generation were divided into TGM control group and TGM treated group randomly. The normal control group included ten normal BC 57L/6 mice at the same age. The mice in treated group were administrated with JWSNS at the concentration of 4 g/mL and the dosage of 50 g/kg per d for 30 d, while the mice in TGM control group and normal control group were administrated with normal saline at the same dosage and the same time.Polymerase chain reaction (PCR) was used to assess the contents of HBV DNA in serum of HBV TGM before and after treatments, whereas blot hybridization was utilized to measure the contents of HBV DNA in the liver of both HBV TGM and normal BC 57L/6 mice.RESULTS: The levels of serum HBV DNA in TGM treated group were remarkably decreased after the treatment of JWSNS (7.662±0.78 vs 5.22±3.14, P＜0.05), while there was no obvious change after administration of normal saline in TGM control group (7.125±4.26 vs 8.932±5.12, P＞ 0.05). The OD values of HBV DNA in the livers of the mice in TGM treated group were significantly lower than those of TGM control group (0.274 ± 0.096 vs 0.432±0.119, P＜ 0.01).CONCLUSION: JWSNS exerts suppressive effects on HBV DNA in the serum and liver of TGM.