OBJECTIVE To observe the efficacy and safety of PEG-interferon alpha-2a (PEG-IFNalpha-2a) treatment on lamivudine (LAM)-resistant chronic hepatitis B (CHB) patients. METHODS Eighty-one patients with lamivudine-resistant HBeAg (+) chronic hepatitis B patients were enrolled and divided into PEG-IFNalpha-2a treatment group (40 cases) and adefovir dipivoxil (ADV) control group (41 cases). Two groups were combined with LAM in the first 12 weeks(w). The ALT normalization rate, the HBV DNA and HBeAg negative rate, and the HBeAg seroconversion rate were observed in 12 W, 24 W, 48 W. RESULTS The ALT normalization rate in 12 W, 24 W of PEG-IFNalpha-2a group was 62.5% and 80.0%. And it was higher than that of ADV group. The HBeAg negative rate and HBeAg seroconversion rate in 48 W of PEG-IFNalpha-2a group were 60% and 57.5% , which were higher than that of ADV group. The difference was statistically significant (P < 0.05). CONCLUSION PEG-IFNalpha-2a treatment of lamivudine-resistant HBeAg (+) chronic hepatitis B is superior to ADV, and its security is well.