This study will select 60 patients diagnosed with hepatitis B. After a thorough medical examination and liver biopsy, subjects will be given lamivudine. The drug will be taken by mouth in tablet form (100 mg) once a day for up to 5 years. Subjects will undergo regular check-ups and after 1 year of therapy be admitted to the Clinical Center for another medical examination and liver biopsy to assess progress. Patients who have benefitted from the therapy will continue taking the medication for up to 5 years. A third liver biopsy will be done during the last year of treatment. The effectiveness of lamivudine will be determined by whether levels of hepatitis B virus decrease in the blood, whether liver enzymes improve, and whether inflammation and scarring decreases in the liver biopsies.