Natural killer (NK) cells are believed to play a role in the progression of human immunodeficiency virus 1 (HIV-1) disease, and NK cell levels are reduced in individuals with chronic HIV-1 infection. To assess the effects on quantity of NK cells and the changes of NK cell receptors in HIV-1 infected children via mother-to-child transmission, the percentage of NK cells is quantified and the changes in the NK cell receptor profiles in 20 HIV-1 infected children who are not progressing into AIDS were examined. The results showed that NK cell percentage was decreased in the HIV-1 infected children. The expression of NKp30 on NK cells was increased, while the expressions of CD16, NKp44, NKp46, NKp80, NTB-A, CD244, KIR2D, KIR3DL1 and NKG2D on NK cells were decreased in the HIV-1 infected children. NK cell cytolytic activity was elevated in HIV-1 infected children. These results indicate that the acute changes in NK cell percentage and NK cell receptors in HIV-1 infected children are different from the HIV-1 infected adult individuals. Moreover, serum concentrations of IL-18 were elevated in HIV-infected children compared to HIV-uninfected controls. These differences probably play a role in protecting against transmission of maternal HIV-1 virus and guiding the therapeutic strategies for HIV-1 infected children.