Acute toxicity study was conducted on a Hepatitis B vaccine (Hepaccine-B-inj.) with mice, guinea pigs, and rabbits, in accordance with the norms suggested by the F.D.A. in U.S.A. Dose ranges were 2 doses/mouse, 5 doses/guinea pig, 10 doses/rabbit. They received the vaccine subcutaneously and intraperitoneally. Thereafter, all animals injected were observed of general signsdaily, and of body weight for two weeks. At the end of the observation period (or at the time of death), all animals received the highest dose group were autopsied and gross observation was made on various organs and tissues. No significant toxicity was noted.