Objective To assess the efficacy of lamivudine in patients with HBeAg positive chronic hepatitis B.Methods MEDLINE, SCI, Current Content Connect, The Cochrane Library, and Chinese Biomedical Database were searched from the beginning to September 2005, and the references of eligible studies were manually screened. R.andomized controlled trials comparing lamivudine with non-antiviral interventions （ placebo, no treatment and standard care ） in patients with chronic hepatitis B were eligible for inclusion. Two investigators independently assessed the quality and extracted the data. Heterogeneity was examined by Chi-square test. Fixed and random effect meta-analysis were used to pool the data. Subgroup analyses were used in treatment course. Results Eleven R.CTs were included （ n = 1 237 ）. All reported the effect of lamivudine （100 mg/d） , and one of them included lamivudine （25 mg/d）. The treatment duration of 52 weeks and less than 26 weeks were reported in eight and three RCTs, respectively. Six RCTs adequately applied randomization, while other five RCTs were not reported in detail. Four RCTs adequately enforced allocation concealment, five RCTs enforced blinding bitterly. The others were not reported in detail. It was found by meta-analysis that, compared with the control, lamivudine （100 mg/d, 52 W） could significantly clear HBeAg [42.6% vs. 13% , RR 3.20, 95% CI （2.33, 4. 38）] and clearHBVDNA [71.78% vs. 20, 36%, RR3.42, 95%CI （2.80,4.19）], normalize ALT [65% vs. 34.9%, RR1.91, 95%CI （1.64,2.21）], achieve HBeAgseroconversion [16.1% vs. 7.29% , RR2.12, 95%CI （1.24,3.80） ] and histology response [57. 9% vs. 26.2%, RR 2. 17, 95% CI （ 1.67,2.81 ） ] ; Lanfivudine （100 mg/ d, 12 W） could effectively clear HBV DNA [ 50.7% vs 3.92% , RR 8.68, 95% CI （1.72,43.74 ） ] , but was not effective in loss of HBeAg, HBeAg seroconversion and normalization of ALT, Lamivudine （25 mg/d） could effectively clear HBV DNA [97.7% vs. 22.2% , RR 4.41, 95% CI （2.86,6.79） ] and improve histology response [59.3% vs. 30% , RR1.98, 95% CI （1.31,2.99 ） ], but was not effective in HBeAg seroconversion. Conclusions Lamivudine （100 mg/ d） is effective in clearing HBV DNA and HBeAg, normalizing ALT and achieving HBeAg seroconversion.