摘要Background Natural killer (NK) cells play critical roles in host immune defense, while the quantities and subset distributions may vary among different races. To address the difference, we compared these variables among Chinese Han, the Caucasians and the Blacks. The study may provide critical background information for both basic research and clinical investigation.Methods Blood samples collected from populations of different races were tested within 12 hours after collection and subsets of NK cells were characterized using flow cytometry.Results The absolute NK count in the Chinese Han was significantly higher than that in the Caucasian. The Han and Caucasian groups showed higher percentages of cytotoxic subset compared to that of the Black group. The percentage of cytokine-producing subset of Chinese Han group was lower than that of Caucasian and Black groups. Black group had a higher percentage of function-unknown NK subset than that of the Hah and Caucasian groups.Conclusion Our data indicated that NK cell count and the distribution of different subsets varied among different races,which should be taken into consideration in related investigations.