Objective To investigate the level of B7-H1 and its counter-receptor PD-1 expression in mDC and different subsets of T lymphocytes in HIV infected individuals in China and to analyze the correlation between the level of B7-H1/PD-1 and disease progression, and to demonstrate that PD-1/PD-L1-dependent inhibition is operating in HIV infected patients.Methods Percentage of B7-H1 and PD-1 expression in mDC, CD+4 T cells and CD+8 T cells from thirty-six untreated HIV infected patients and 20 health controls were selected and detected by flow-cytometry, its correlations with CD+4 T cell absolute counts and plasma viral loads were analyzed.Results The percentage of B7-H1 expression in mDC, CD+4 T cells and CD+8 T cells (mean 15.21, mean 20.63, mean 13.5)were higher than that of health controls (all P<0.05).The percentage of PD-1 expression in CD+4 T cells and CD+8 T cells (mean 17.91, mean 19.21)were higher than that of health controls (P<0.05, P<0.05). The level of B7-H1 and PD-1 expression were inversely correlated with CD+4 T-cell counts(mDC+B7-H1+:r=-0.647, P<0.01;CD+4B7-H1+:r=-0.489, P=0.002;CD+8B7-H1+:r=-0.372, P=0.026;CD+4PD-1+:r=-0.374, P=0.025;CD+8PD-1+:r=-0.455, P=0.005) and positively correlated with HIV viral load(mDC+B7-H1+:r=0.662, P<0.01;CD+4B7-H1+: r=0.426, P=0.01;CD+8B7-H1+:r=0.531, P=0.001;CD+4PD-1+:r=0.362, P=0.03;CD+8PD-1+:r=0.380, P=0.022).Conclusion The level of B7-H1 and PD-1 expression was associated with HIV disease progression, which provides a useful marker to define disease progression of HIV infection.