ABSTRACT:Objective To study the dynamic changes of T lymphocyte subsets in severe acute respiratory syndrome(SARS)patients. Methods Sequential anti-coagulated blood samples were collected from 62 seropositive SARS patients during the first week,the second week,the first month,the 2nd-3rd month,and 1 year after disease onset.T-lymphocyte subsets including CD4+T cells,CD8+T cells,and naive and memory CD4+T cells were detected by flow cytometry. Samples from 56 healthy blood donors were also detected as healthy controls. Results A rapid restoration in T-lymphocyte subsets was observed during a short period after infection. During the 2-3 months after disease onset,CD8+T cell count returned to the normal level. At the same time point,CD4+T cell and naive CD4+T cell counts increased to（534±197）/mm3 and（175±75）/mm3 respectively.Total lymphocytes,T lymphocyte,CD4+T and naive CD4+T cell were still significantly lower than the normal levels even one year after disease onset. Conclusion The periphery T lymphocyte subsets in SARS infection shows transient decrease and then rapid recovery.