Previous studies on IFN-alfa and lamivudine combination treatment of chronic hepatitis B showed marginal benefit over lamivudine monotherapy. In these studies, lamivudine was either started 8 weeks prior to IFN-alfa or simultaneous with IFN-alfa. Recently, we have performed a study comparing the efficacy of polyethylene glycol-interferon alfa-2b (PEG-Intron A) and lamivudine versus lamivudine monotherapy for 1 year in the treatment of chronic hepatitis B. In our protocol, PEG-Intron A is started 8 weeks before the commencement of lamivudine, and PEG-Intron A is given for 32 weeks while lamivudine is given for a total of 52 weeks. Our published results suggested PEG-Intron A and lamivudine combination treatment is far superior to lamivudine monotherapy (end of treatment virological response 92% vs 20%, p=0.0015). We are not certain whether the benefit of PEG-Intron A and lamivudine combination in our study is due to our staggered regime, the superiority of PEG-Intron A over IFN-alfa, or both. The aim of this study is to investigate the best treatment regime of PEG-Intron A and lamivudine combination in terms of viral clearance.