In Yamaguchi University Hospital, 93 cases had hospital accident with hepatitis B virus(HBV) from 1983 to 1987. Most of them were due to accidental picking of the skin with HBV-polluted needle. To prevent the occurrence of actue hepatitis B among the medical staff, vaccination of HBsAG was performed in 350 cases from 1986 to 1987. 93 cases out of them were vaccinated in accordance with the protocol. Appearance of HBsAb was observed in 80(86.0%)out of them. Higher response to vaccine was recognized particulaly in female and younger cases below 40 yeas old.