Abstract: Objective To investigate the change of specific immunoreaction of T cells before and after radiotherapy in the patients with nasopharyngeal carcinoma,and to search the factors correlated to the curative effect. Methods Forty-one nasopharyngeal carcinoma patients were investigated in the study.10 ml blood were taken before and 3 months after the radiotherapy， PBMCs were separated and specific responses T cell to EBV peptide segments such as peptide,LMP1,LMP2,EBNA1 and EBNA3 were measured by using ELISPOT assay. Results We found that,after radiotherapy,there are 36 cases of CR，4 cases of PR，1 case of PD,whose frequency of CTL cells in peripheral blood response to LMP1 significantly increased(P=0.004),while had no statistical significance in the respone to LMP2、EBNA1 and EBNA3.The frequency of CTL cells in the groups with different curative effect responsed to LMP1 also had statistical significance. Conclusion ELISPOT assay can be used to detect the specific responses of T cell to LMP1 before and after radiotherapy in the patients with nasopharyngeal carcinoma.This provides basic data for the development of potential therapy in combination of immuno-and radiotherapy,as well as for the evaluation of the treatment to these patients.