Sixty rural children who were seronegative for HBV markers received three doses of 10 microgram of a new Hepatitis-B vaccine, Revac-B (1 ml of vaccine contains 20 microgram recombinant surface antigen) that was formulated from hepatitis-B surface antigen expressed in a recombinant strain of Saccharomyces cerevisiae. Vaccines were administered on a 0, 30 and 60-day schedule. Levels of anti-HBs titres were determined on the 30th, 60th and 90th days following the initial injection. None of the participants in the trial had serious adverse reactions and the frequencies of minor side effects were minimal. No clinically important adverse effects which could be considered as directly related to the vaccination were recorded. The volunteers showed a very good immune response and were seroprotected on the 30th day after the first dose of vaccination. The present study revealed that the new vaccine, Revac-B is highly immunogenic and is well tolerated.