Abstract: Objective To investigatethe expressions of NKG2A, NKG2C receptors and their ligand HLA-E in decidua of preeclampsia patients. Methods Decidua tissues were collected from 30 patients with mild preeclampsia, 42 patients with severe preeclampsia and 46 normal pregnancy as contrast. The expressions of NKG2A, NKG2C protein were detected by immunohistochemitry and mRNAs of NKG2A, NKG2C and HLA-E genes were detected by RT-PCR.Results The expression of HLA-E mRNA was significantly decreased in preeclampsia, especially in severe preeclampsia patients (P<0.05); The mRNA and protein expression of NKG2A, NKG2C in severe preeclampsia group were significantly higher than that in normal pregnancy group (P<0.05); In the severe preeclampsia group,the ratio of expression level of NKG2A and NKG2C was significantly lower than that of normal group and the mRNA and protein expression ofNKG2C receptor were both significantly higher than that of NKG2A (P<0.05); The mRNA expression level of HLA-E, NKG2A and NKG2C were closely related with clinical and biochemical indexes,such as blood pressure of late pregnancy and 24-hour proteinuria. Conclusion The decreased expression of HLA-E and the unevenly increase of NKG2A and NKG2C may involve in the pathogenesis of preeclampsia.