Objective To study the alternations of regulatory T cells in early HIV infected patients and its association with disease progression.Methods Fifty-one untreated HIV infected patients were enrolled and divided into 3 groups according to their infection time and CD+4 T cell levels(30 early HIV infected patients,15 typical progressors,6 AIDS patients).Twenty normal controls were enrolled.There were no significant differences between the age and sex among four groups.Blood was drawn by venipuncture from each subject in EDTA tubes and the levels of CD+4 CD+25 Foxp3 + regulatory T cells were detected by FACSAria flow-cytometry.Spearman correlation was used to detect association between CD+4 CD+25 Foxp3 + regulatory T cells and the absolute CD+4 T cells,viral load and activation of T cells.Results The levels of CD+4 CD+25Foxp3+ regulatory T cells showed the tendency of increasing tendency from normal control to early HIV infected patients,asymptomatic HIV infected patients and AIDS patients.Early HIV infected patients was significantly lower than that in AIDS group [3.79(2.11 - 5.43) % vs 8.09(4.90 - 8.90) %,Z = - 2.29,P = 0.022].The levels of CD+4 CD+25 Foxp3 + Treg cells were associated with viral set point(r = 0.479,P =0.038) and inversely associated with CD+4 T cells(r = -0.455,P =0.011) and closely associated with HLA-DR expression on CD+3 T cells(r = 0.533,P = 0.002).Conclusions The ratio of CD+4 CD+25 Foxp3 +regulatory T cells of early HIV infected patients was significantly increased and associated with viral set point and CD+4 T cell counts,which indicate that alternation of regulatory T cell may be an important factor contributing to the disease progression in early HIV infection.