Am investigation was done to identify the best and safe dosage of magnesium isoglycurrhizinate in treating hepatitis B.All 1 50 cases suffering from hepatitis B were randomly divided into five groups as A,B,C,D,E.Cases in group A were treated with magnesium isoglycurrhizinate in 100 mg per day for two weeks sololy,and in group B,C,D,E in 150 mg,200 mg,250 mg and 300 mg respectively.The changes of symptoms,index of hepatic function,clinical effective rates and side-effects were observed from treatment beginning to the end.The results that revealed there were no different effects among groups B to E,but less therapeutic effects in group A,and no obvious side-effects in all groups,suggesting that 150 mg dosage of magnesium isoglycurrhizinate should be a safe and the best dosage for treating hepatitis B.