90 patients with chroni c active or chroulc persi sten t hepatitis type B were divided into threegroupe at random。Patients in group one were treated with vidarabine monophosphate(Ara- AMP)and thymosin; patients in grroup two were treated with Ara-AMP and HB vaccine. While patientsin groups three served as control. By the end of 3months after t reatment

the rates of HBeAg frompositive to negative were 40%、 36.7%and 13.3%hgroup one

group two and group threerespectively

and the rates of HBV- DNA from pesitive to negative were 46.1%

48%and 12%ineach group respectively

and negative conversion rates of HBeAg and HBV-DNA in the twotreament groups were statistically significant exceptfor the negateve conversion rates of HBe Agof group two by the end of treatinent.HBsAg of three groups remained positive during the routineobservation period .The Lowering of ALT and AST seemed to be same effective in group one and group two

was not statisticdly significant.The side effect of Ara- AMP was minor in degree

andouly one patient felt severe headache.