From October 1990 to May 1993, 300 students aged 18 to 20 years in Xian were studied to evaluate the efficacy of plasma-derived hepatitis B vaccine made in five factories. AntiHBs titer in 5 vaccinated groups reach the highest at the twelfth month after the first injection and decreased afterwards. The positive rate of anti-HBs decreased slowly, but the titer of anti-HBs fell sharply. Compared with the control group, the differences were all significant. The results showed that the efficacies of hepatitis B vaccine made in five factories were similar. The protection rate of hepatitis B vaccine against HBV infection was 79.22%.