Eligible patients have to be HIV, HDV and HCV negative and will have to i) give their written informed consent; ii) have a B hepatitis grade over or equal to F2 with the Metavir score, DNA HBV greater than 105 copies/mL (or 104 copies/mL if Ag Hbe -) , ALAT greater than 1.3 times the upper limit of the normal; iii) accept to have a liver biopsy and to be followed for this protocol at the DHP. After a 3-month treatment with Lamivudine, patients whose viral load is negative or at least decreased by 4 Log will be randomized to the same treatment for a further 9-month period or to the same treatment combined with 12 injections of vaccine over 6 months. The main endpoints are undetectability of HBV DNA blood level 12 months after treatment initiation and 6 months after the end of the treatment. Secondary endpoints will be HBV DNA blood levels at 3, 6, 9 and 12 months after the end of the treatment, transaminases blood level, Lamivudine treatment compliance, the feasibility of the vaccine injections schedule, safety, AgHBe seroconversion (in positive patients) and negativation of AgHBs. Two hundred ten patients have to be included (70 in the Lamivudine group, and 140 in the Lamivudine + vaccine group) in order to show a difference of at least 20% in the percentage of patients with an undetectable viral load at 12 months (70% expected under Lamivudine monotherapy), with a power of 90%, an alpha risk equal to 5% and a bilateral test. Patients with a virological failure will be maintained or retreated with Lamivudine. For the patients with an YMDD mutation, a treatment with Adefovir Dipivoxil will be possible. Patients' inclusion is planned to start in January 2005 and end after 12 or 18 months. Patients will be treated during one year and followed one year without treatment in the study protocol, and then will be managed if necessary