We studied the infectious effect of SARS-CoV virus on juvenile and adult Brandt's Vole (Microtus brandtii) by nasal cavity spraying method (CCID_ 50 is 105.7). SARS virus caused serious deaths in adults. The death adults showed hemorrhage from mouth, nasal cavity and intestine, hemorrhageious interstitial pneumonia and gore in liver, spleen and kidney. The survival adults showed local hemorrhagic spot in lung and emphysema, but the other organs showed no pathological abnormality. SARS virus caused no deaths in juveniles, but locomotion of infected juveniles became slower. In the early stage, there was local pneumonia in lung and SARS viruses were isolated from the pathological tissue. Only one control juvenile lived and the infected juvenile showed local pneumonia in lung. The results demonstrated that SARS-CoV infected Brandt's vole seriously and adults were more susceptive to SARS-CoV than juveniles. The Brandt's vole may be a potential animal model for SARS research.