Data on interferon-based treatment among chronic hepatitis B patients who have failed previous anti-viral treatment is scanty. It is uncertain whether pegylated interferon-alfa-2a treatment will be effective in this group of patients. This is a single-center, pilot study on the virological response of chronic HBV infection to pegylated interferon-alfa-2a among patients who have failed anti-viral treatment in the past. This study will investigate the HBV DNA suppression (and HBeAg seroconversion among HBeAg positive patients) pegylated interferon treatment at 24 weeks after end of treatment.