AIM: To evaluate the efficacy and safety of lamivudine treatment of chronic hepatitis B disease in pregnancy.METHODS: The study group was comprised of 38 chronic HBV patients who were diagnosed pregnant duringlamivudine treatment and voluntary to continue the same therapy. The control group was from documented patient data in the literatures. We compared the following parameters with those of a control group: anti-HBV efficacy, complications of pregnancy (abortion, preterm birth, neonatal asphyxia, fetal death, and congenital anomaly), incidence of HBV-positive babies and developmental anomalies in pregnant women treated with lamivudine. RESULTS: The blocking rate of lamivudine treatment was significantly higher than that of active vaccine immunization for babies with double-positive (HBsAg/HBeAg) mothers with 30-30-10 μg doses of vaccine (74.07%) and with 30-20-10 μg (64.87%). The natural vertical HBV transmission from mother to infant of double-positive mothers was 100% (10/10). No pregnancy complication was noted during the observation period, but in the control group the incidences of pregnancy complication were 16.67% (abortion), 43.02%(preterm), 15.62% (neonatal asphyxia), and 4.49% (fetal death), 10.0% (congenital anomaly). No HBV-positive newb was detected and no developmental anomaly was found in the study group.CONCLUSION: Lamivudine is helpful to prevent matal infant HBV transmission and may reduce the complications of HBV-infected pregnant patients.