Infants of HBsAg-positive mothers (Group I) as well as those born to women without HBV markers (Group II) were vaccinated with a 10 micrograms dose of a recombinant DNA hepatitis B vaccine within 24 hours after birth according to a 0, 1, and 2 month schedule, with a booster dose planned 12 months later. Vaccination results in 14 (Group I) and 47 (Group II) neonates showed that at two months after the third dose of vaccine, 86% (6/7) and 100% (37/37), respectively, seroconverted, with anti-HBs geometric mean titres of 80 IU/l and 266 IU/l in the respective groups. No adverse reactions to the vaccine were observed. These preliminary results indicate that the recombinant DNA hepatitis B vaccine is safe and highly immunogenic in newborns.