Abstract: Objective This study was performed to fully understand the epidemic rules and changes since the monitoring of HFRS was carried out in Baoji City．and to provide the basis for further formulating measures of prevention and treatment of HFRS．Methods The data for epidemic situation and monitoring of HFRS from 1984 to 2004 in Baoji City were analyzed．Results The incidence tended to drop by stage，and the mortality or fatality rate decreased continuously．The valley of Weihe River was the main focus of infection，and the epidemic area was transformed from a type of Apodemus to a mixed type．The field dominant species was apodemus agrarius，and indoor species tended to transform from rattus flavipectus to sewer rat．The index of animals with virus showed a highly positive correlation with incidence，and the rate of subclinical infection was high among people of the valley of Weihe River．Conclusion The prevalence of HFRS is more related to natural，economic and social factors．In these years，some comprehensive measures for HFRS prevention and control，mainly vaccination，health education，and rat prevention，have been taken，which showed a significant effect on the prevention and control of HFRS．Carrying out monitoring work systematically has an instructive significance for the forecast of epidemic situation．