SUMMARY. This open label study was initiated to assess the safety and efficacy of lymphoblastoid interferon-α (IFN-α) and thymosin α1 (Tα1) in the treatment of 11 patients with chronic hepatitis B, who had failed to respond to standard IFN-α2b therapy, and in four interferon naive patients. These fifteen hepatitis B surface antigen (HBsAg) positive and serum hepatitis B virus (HBV) DNA positive patients were given Tα1 (1 mg) subcutaneously (sc) on 4 consecutive days. Low-dose lymphoblastoid IFN-α (3 MU) was administered intramuscularly (IM) on the fourth day. Beginning with the second and for the subsequent 25 weeks, patients self-administered Tα1 twice weekly in the morning followed, 12 h later, by 3 million units (MU) lymphoblastoid IFN-α. Patients were followed-up for 12 months. Nine (60%) of the 15 patients, including six (55%) of the 11 patients previously treated with IFN-α2b, responded by losing serum HBV DNA and normalizing alanine aminotransferase (ALT) values. Six of the nine responders seroconverted to HBsAg negativity. Significant improvements in the Knodell histological activity index were observed in the responders and no significant adverse effects were observed. Combination low-dose lymphoblastoid IFN-α and Tα1 treatment may provide a safe and potentially effective therapeutic approach in chronic hepatitis B. These results require confirmation in future randomized controlled studies.