ObjectiveTo analyse hepatitis B virus（HBV） reactivation induced by glucocorticoid and the efficacy of lamivudine on the prevention and treatment of HBV reactivation in patients with HBV infection after receiving glucocorticoid therapy .MethodsOne hundred and twentysix patients with HBV infection receiving glucocorticoid treatment were divided into three groups according to serum alanine transaminase (ALT) and HBV DNA levels: 39 patients with normal serum ALT level and negative HBV DNA (group A), 60 patients with normal serum ALT level and HBV DNA level at ≥103 copies/mL(group B), and 27 patients with ALT ≥two fold of normal value upper limit and HBV DNA level ≥104 copies/mL (group C).Patients with and without lamivudine treatment were followed up by testing serum ALT and HBV DNA every three to six months for 12-18 months.ResultsFortyseven patients in group A and B did not receive lamivudine treatment, 29 of whom (61.70%) had obvious HBV DNA elevation , 31 (65.96%) with ALT elevation ,and 10 (21.28%) with liver function decompensation during glucocorticoid treatment follow up; In group A and B patients receiving lamivudine treatment, there were only 4 cases(7.69%) developed recurrence. The efficacy of lamivudine therapy in group C was only about 37.04% (10/27), which was significantly lower than that（92.31%） in patients without activation of hepatitis B (χ2=27.82,P<0.01).ConclusionGlucocorticoid therapy can induce reactivation of HBV infection, recurrence of liver inflammation and decompensation in patients with HBV infection. Lamivudine can efficiently control HBV reactivation induced by glucocorticoid in chronic hepatitis B patients.The efficacy of preventive therapy is obviously better than the delayed therapy.