The aim of this study was to examine the relationship between peripheral natural killer (NK) cells and recurrent miscarriage by improved methods. Peripheral NK cell measurement was carried out using flow cytometry of morning blood samples obtained in the early follicular phase, analysed within 8 h of collection. Eighty-five Chinese women with recurrent miscarriage who previously tested negative for autoantibodies, and 27 control subjects who were not using any hormonal methods for contraception, were recruited. No significant difference was found in the number of peripheral NK cells and their subsets between women with recurrent miscarriages and control subjects. Only 5% of women with recurrent miscarriage had high peripheral NK cells. The number of previous miscarriages did not appear to have an impact on the number of NK cells. In conclusion, there appears to be limited value in the routine measurement of peripheral NK cells in women with recurrent miscarriage.