GROUP B: Patients with HBeAg (+) or HBeAg (-) decompensated chronic hepatitis B who did not discontinue treatment in their previous study due to an efficacy response and required further treatment. Patients treated with telbivudine in study 2301 were enrolled to group B and the total telbivudine treatment time (starting from feeder study baseline to the end of the on-treatment period in study 2303) was 208 weeks. For patients treated with lamivudine in study 2301 and enrolled into group B, the total telbivudine treatment time was 104 weeks.