Abstract: Objective To investigate the expression of CD25+ lymphocytes in nasopharyngeal carcinoma (NPC) tissue and the influence of Epstein-Barr virus (EBV) infection on CD25 expression. Methods Immunohistochemistry was used to detect CD25 expression in the NPC tissues and in situ hybridization employed to detect EBV infection with chronic nasopharyngitis tissue as the control sample. Results Significant difference was noted in the expression of CD25+ lymphocytes between NPC and chronic inflammatory tissues. The expression was higher in undifferentiated NPC than in keratinizing squamous cell carcinoma and non-keratinizing carcinomas. The NPC tissue was all EBV-positive except for one sample, which was identified as keratinizing carcinoma, but the control samples were all negative for EBV infection, which was correlated with CD25 expression. Conclusion The expression of CD25+ lymphocytes is higher in NPC tissues and correlated to EBV infection.