Abstract :Acute hepatitis by hepatitis B virus (HBV) genotype A causes long duration of hepatitis, and the carrier rate after acute infection is approximately 10%. The genotype A hepatitis has become the most common acute infection linked to horizontal transmission among young people in recent years. Increases in HBV genotype A-carrier mothers are expected in the near future in Japan, and prophylaxis against mother-to-child transmission for hepatitis B virus genotype A-carrier mothers will therefore be important in suppressing expansion of this viral infection. This report describes that infants born to HBV genotype A-carrier mothers have begun to appear in Japan and prevention of mother-to-child transmission (MTCT) was performed by administration of immunoglobulin derived from genotype A virus antigen with subsequent inoculation of vaccine derived from genotype C virus antigen.