We evaluated whether V-5 Immunitor (V5), tableted immunotherapeutic preparation comprising heatinactivated HBV antigens from pooled blood of HBV- and HCV-infected donors, may produce clinical benefit through induction of oral tolerance and reduction of immune-mediated liver injury. Once daily dose of V5 was administered per os to 10 patients with chronic hepatitis B in an open label study that lasted one month. Every patient who entered the study had elevated liver enzyme levels, which at the end of study have decreased in 100% of analyzed patients. The reduction was highly significant, from 112.4 to 44.4 U/L (P=0.00009) and 118.8 to 46.1 U/L (P=0.0032), for ALT and AST respectively. In addition, half of intent-to-treat patients who were HBV surface antigen (HBsAg) positive at study entry, became negative after one month on V5 (P=0.0098). All patients, except one, reported complete recuperation from hepatitisassociated clinical symptoms present at baseline (P=0.0016). No adverse events were observed at any time. Favorable biochemical, virological and clinical responses indicate that V5 is safe and effective means for immunotherapy of chronic hepatitis B. Placebo-controlled, randomized study is required to confirm these findings.