Abstract: Objective To analyzed T cell subsets and regulatory T cells of aplastic anemia patients,and discuss the relationship between aplastic anemia and T cell subsets and regulatory T cells. Methods Thirty cases of aplastic anemia(aplastic anemia group) were assigned into severe aplastic anemia group and non-severe aplastic anemia group,while 30 normal subjects were recruited as control group.The peripheral blood CD4⁺CD25⁺ regulatory T cells and T cell subsets expression was compared among the three groups. Results The expressions of peripheral blood CD4⁺CD25^high and CD4⁺CD25⁺CD127^low in aplastic anemia group were lower than those in the control group(P<0.05),but CD4⁺CD25⁺CD127^high was higher than that in the control group(P<0.05).The peripheral blood CD3⁺CD4⁺ and CD4/CD8 in aplastic anemia group were lower than those in the control group(P<0.05),but CD3⁺CD8⁺ was higher than that in the control group(P<0.05).The expression of peripheral blood CD4⁺CD25^high and CD4⁺CD25⁺CD127^low in the severe aplastic anemia group were lower than non-severe aplastic anemia group(P<0.05),but CD4⁺CD25⁺CD127^high was higher than non-severe aplastic anemia group(P<0.05).The peripheral blood CD3⁺CD4⁺ and CD4/CD8 of severe aplastic anemia group were lower than non-severe aplastic anemia group(P<0.05),while the peripheral blood CD3⁺CD8⁺ of severe aplastic anemia group were higher than non-severe aplastic anemia group(P<0.05). Conclusion T cell subsets and regulatory T cells of aplastic anemia patients are abnormal.The pathogenesis and severity of aplastic anemia may be correlation with T cell subsets and regulatory T cells.