To investigate the expression of annexin V in the decidua tissues of preeclampsia patients and explore its clinical significance.Real-time PCR, Western blotting and immunohistochemistry were employed to detect the mRNA and protein expressions of annexin V in the deciduas from 35 normal pregnant women at full term, 38 early onset severe preeclampsia patients and 33 late onset severe preeclampsia patients.Annexin V was found on the cell membrane and in the cytoplasm of the decidual cells and stroma. Both the mRNA and protein of annexin V expressions in the decidua tissues were significantly different between normal pregnancy group and early or late onset severe preeclampsia group (P<0.05), being the highest in normal pregnancy group and the lowest in early onset severe preeclampsia group.The low expression of annexin V in the deciduas might participate in the hypercoagulability state in preeclampsia patients.