Abstract： Objective The aim of this study was to verify that NK cells were one type of the virus reservoir cells,and to observe whether NK cells,T lymphocytes and monocyte are long-term viral reservoir cells of HIV-1.Methods A group of 15 chronic HIV-l-infected adults,who received 4 ～7 years-HAART treatment[ mean(62.45 ± 13.53) months],participated in this study for crosssectional study.After the ethical approval was obtained,a volume (40 ml) of peripheral whole blood was obtained from each patient.The number of T cell subgroup was detected with flow cytomctry.The NK cells,T lymphocytes,and monocytes were separated from peripheral blood mononuclear cells (PBMC) using microbead sorting method ( CD3 +,CD14 + and CD56 + antibody microbeads).DNA was extracted with human DNA kit.Real-time fluorescent quantitative PCR was used to detect the serum HIV RNA and DNA in the three types of cells.Graphpad prism5 software was used to analyze the collected data.Results Among 15 patients with 4 ～ 7-year-HAART treatment,plasma HIV-1 RNA of all the patients are undetectable; however,HIV-1 DNA was detected in 6 patients'T lymphocyte [ mean(2.03 ± 0.48)logl0copies/106 cells],in 4 patients'Nk cells [mean ( 1.82 ± 0.32 ) logl0copies/106 cells ],and in 2 patients'monocytes [ mean( 1.75 ± 0.19) logl0copies/106 cells ].Conclusions These findings revealed that NK cells were another important HIV cellular reservoir besides T-lymphocytes and monocytes,and T-lymphocytes might be the main long-lasting HIV reservoir.