It has been suggested that natural killer (NK) cell activity and Th1 immunity may be involved in the pathogenesis of preeclampsia. This study aimed to investigate the immunophenotypes of NK cells and type 1/type 2 immunity in both decidua and maternal peripheral blood between normal (n=11) and preeclamptic pregnant women (n= 20) by flow cytometry. The results showed that no significant difference was observed between patients and controls by detecting CD56(+) CD69(+) and CD56(+) CD94(+) NK cells in both peripheral blood and decidua. Moreover, in preeclamptic patients, decreased percentages of Tc2 and Th2 cells and the increased ratios of Tc1/Tc2 were determined in both decidua and maternal peripheral blood. In addition, the ratio of Th1/Th2 in peripheral blood also increased. There was no significant difference of immunophenotypes of uNK cells between preeclampsia and normal pregnancy. Local decidua and systematic immunity did not correlate with each other. These results suggest that the type 1/type 2 immunity shifted to type 1 immunity including Th1 and Tc1 cells may contribute to the patho-genesis of preeclampsia.