Abstract: The purpose of this report was to observe the safety,serological and epidemiological efficacy of Type I inactivated vaccines against HFRS that was purified from mouse brains and supplied by Institute of Biological products Lanzhou.Methods Immunoflures-cent antibody assay was used in testing specific IgG antibody and Mcro-CPE method was used in testing the titer of neutralizing antibody.There is cohort study for epidemiological efficacy.Results This vaccine was safe.The rate of genernal response was 3.19%,and the rate of medium and strong response was 1.82%.Two weeks after three doses of infection before reinforced two weeks one year and two years after reinforced The rates of seroconversion of neutralizing antibody were 31.14%.9.33%.87.50%.53.85%.35.80% and 30.10% respectively.The rates of seroconversion of immunofluorescent antibody were 84.91%,22.50%,85.00%,15.79%,9.52% and 10.00% respectively.This vaccine has good efficacy in prevention disease.After three doses of injection there were no patients in the immunized group and eight cases in the control group,so the protection rate was 100%.After the epidemic peak,the inoculated individuals didnt show any clinical symptom but increase of immunofluorescent antibody was four times more than before.Till now we haven t find any antibody dependent immunization enhancement phenomenon among the inoculated population.Chonclusion:The type I vaccine(supplied by Institute of Biolocal Products.Lanzou) was safe and epidmiologically effective.We also offered some suggestions on the immunological strategy.