Abstract: OBJECTIVE To investigate the expression levels of CD₈₀, CD₈₆ and CD₄⁺CD₂₅⁺ regulatory T cells in peripheral blood in patients with autoimmune hemolytic anemia/Evans syndrome and its clinical significance. METHODS Sixty patients with autoimmune hemolytic anemia/Evans syndrome were enrolled in our hospital from January 2014 to December 2017. Among them, 39 patients in the seizure group and 21 patients in the remission group. In the same period, 28 healthy volunteers were randomly selected as the control group. The expression levels of lymphocyte costimulatory factors CD₈₀, CD₈₆ and CD₄⁺CD₂₅⁺ regulatory T cells in the peripheral blood in the three groups were compared.RESULTS The expression of CD₈₀, CD₈₆ and CD₄⁺CD₂₅⁺ regulatory T cells in the AIHA/Evans syndrome group were（7.21±1.84）%,（6.23±4.42）% and（2.83±1.75）%, respectively. Levels of CD₈₀, CD₈₆ in the seizure group were significantly higher than that in the remission group and the control group（all P＜0.05）; the expression level of CD₄⁺CD₂₅⁺ regulatory T cells in the seizure group was significantly higher than that in the in the remission group and the control group（P＜0.05）. But there was no significant differences of CD₈₀, CD₈₆ and CD₄⁺CD₂₅⁺ regulatory T cells levels in the remission group than that in the control group. CONCLUSION The expression levels of CD₈₀, CD₈₆ and CD₄⁺CD₂₅⁺ regulatory T cells in peripheral blood in patients with AIHA/Evans syndrome were significantly increased. CD₈₀, CD₈₆ and CD₄⁺CD₂₅⁺ regulatory T cells may play an important role in the pathogenesis of AIHA/Evans syndrome.