Hemorrhagic fever with renal syndrome (HFRS) is caused by hantavirus infection. Although host immunity is thought to be involved in the pathogenesis of HFRS, the mechanism remains to be elucidated. A mouse model of HFRS, which showed renal hemorrhage similar to that seen in patients, has been developed previously. In this study, we aimed to clarify whether CD4+ and CD8+ T cells are involved in the development of renal hemorrhage in the mouse model. At 2 days before virus inoculation, CD4+ or CD8+ T cells in 6-week-old BALB/c mice were depleted by administration of antibodies. The CD4+ T cell-depleted mice developed signs of disease such as transient weight loss, ruffled fur and renal hemorrhage as in non-depleted mice. In contrast, the CD8+ T cell-depleted mice showed no signs of disease. After determination of CTL epitopes on the viral glycoprotein in BALB/c mice, the quantity of virus-specific CTLs was analyzed using an MHC tetramer. The quantity of virus-specific CTLs markedly increased in spleens and kidneys of virus-infected mice. However, the quantity in high-pathogenic clone-infected mice was comparable to that in low-pathogenic clone-infected mice. We previously reported that the high-pathogenic clone propagated more efficiently than the low-pathogenic clone in kidneys of mice during the course of infection. Therefore, there is a possibility that the balance between quantities of the target and effector is important for disease outcome. In conclusion, this study showed that CD8+ T cells are involved in the development of renal hemorrhage in a mouse model of HFRS.