Abstract: Objective To study the geographic epidemiological charactristics of epidemic hemorrhagic fever in Longyou county.Methods Animal hosts in southern area were investigated. The serum of the patients were collected to be identified. The test group and controlled group were sampled from the people at the age of 16 to 60. To measure the effectiveness of the vaccine, the serum antibody titer of the inoculated was tested by the method of IFA and MCPENT before inoculation and after inoculation and boosted inoculation.Results 3 703 cases were reported from 1968 to 2001 in Longyou county,and the incidence rate was 30.35/100 000 annually.76 patients died and the fatality rate was 2.05%.Epidemic hemorrhagic fever was primarily a diease of the male peasants of the youth adults.Most infections happened in November to next January and May to July,Apodemus mode was the main type.The infection was in control after the vaccine was used,only 33 cases of epidemic hemorrhagic fever occurred in the year after inoculation and the protection rate of 6 years was 94.32%.Conclutions Longyou county belonged to mixed epidemic area of epidemic hemorrhagic fever and the Apodemus mode was primary,the vaccine had a distinct epidemiological effectiveness of prevention.