Abstract: Objective To evaluate the efficiency of lamivudine or/and adefovir dipivoxil for the treatment of chronic hepatitis B（CHB）patients with hepatitis B virus tyrosine-methionine-aspartate-aspartate（YMDD）mutations. Methods Fifty-six hepatitis B patients with YMDD mutation of lamivudine-resistant HBV were collected and randomly divided into two groups，both of the two groups were treated with Silibinin and Diammonium Glycyrrhizinate before. Patients were assigned to receive adefovir 10 mg/day and lamivudine 100 mg/day（Group A）or adefovir 10 mg once daily and lamivudine 100 mg once daily combination during first 12 weeks，and then stop lamivudine and continue adefovir（Group B）. The efficiency was determined by comparison of viral loads，alanine aminotransferase（ALT）level and hepatitis B e antigen seroconversion pre-and post treatment after 96 weeks． Results The viral loads and ALT level of the two groups were decreased significantly. The negative rate of HBV DNA in group A was 96.4% on the 96 weeks，while in group B was 75.0%（P<0.05），the negative rate of HBeAg were 89.2% and 57.1% in the two groups，respectively（P<0.05）. The ALT normalization rate were 96.4% and 85.7%（P＞0.05），respectively. One patient had resistant mutation in group A and four patients in group B. No adverse reactions occurred in the study. Conclusion The present study confirmed that the combination of lamivudine with ADV was superior for the treatment of CHB patients with YMDD mutation.

Key words: Adefovir, Lamivudine, Hepatitis B, YMDD mutation