Abstract: ObjectiveThe levels of EBV-LMP2 special CTLs, EBV-DNA and T cell subsets in peripheral blood of NPC patients are analyzed to summarize the change patterns and characteristics. Methods Serum samples were obtained from 35 NPC patients waiting for radiotherapy, 40 NPC patients treated with radiotherapy and 30 volunteers without NPC.ELISPOT assay was used to evaluate the levels of EBV-LMP2 special CTLs.RT-PCR and flow cytometry were employed to detect EBV-DNA loads and T cell subsets contents,respectively. Results The positive percentages of EBV-LMP2-specific CTLs were obviously different among three groups；the healthy individuals appeared of highest response, the next was post-treated NPC patients.The positive percentages of EBV-DNA in NPC patients were higher than that in normal controls.Besides, the positive percentage of pre-treated patients was higher than that of post-treated patients.The positive percentage had a negative correlation between EBV-LMP2 special immune response and EBV-DNA.The percentages of CD3+， CD4+ T cells and the CD4+/CD8+ ratios in the pre-treated NPC group decreased；the percentage of CD8+ T cells and the CD4+CD25+ Tr cell level increased. Conclusion The special activity of CTLs in pre-treated NPC patients was lowest and correlated with the EBV-DNA load.Enhancing the response of CTLs may improve the effect on preventing and curing the EBV associated tumors.EBV-DNA load could reflect the tumor load and effectiveness of therapy in some way.The CD3+ and CD4+ T cells in peripheral blood of NPC patients decreased obviously；the levels of CD8+ T cells and CD4+CD25+Tr cell increased.The detection of the T cell subsets would be helpful to the treatment and prognosis judgement of NPC patients.