Objective To investigate the expression of miR⁃155，a regulator of T cell immune response，in HIV⁃1 patients′ T cells，as well as its relationship to T cell immune activation and exhaustion. Methods We con⁃ ducted a cross ⁃sectional study with 71 HIV ⁃1 patients who responded well to antiretroviral therapy and 76 patients who did not.CD4+ and CD8+ T cells were isolated and RNA was extracted. MiR⁃155 levels were detected by quantita⁃ tive PCR. Immune activation and exhaustion of T cells were detected by flow cytometry. Results The levels of miR⁃ 155 in T cells，and T cell activation and exhaustion in HIV⁃1 patients were increased compared with healthy controls （P < 0.01），which were much higher in poor responders than in good responders（P < 0.05）. MiR⁃155 was found to be associated with immune activation and T cell exhaustion in HIV⁃1 patients（P < 0.01）. Conclusion Our find⁃ ings suggest that miR⁃155 levels in T cells of HIV⁃1 patients are increased and associated with T cell activation and exhaustion，and that it could be employed as a biomarker to assess T cell activity in HIV⁃1 patients.