Abstract： Objective To investigate the expression of heat shock protein 70 (HSP70) in maternal serum,umbilical cord blood and placenta of patients with hypertensive disorders complicating pregnancy (HDCP) and to discuss its role in the pathogenesis of HDCP.Methods Totally 90 patients with HDCP were recruited as HDCP group,and were devided into three subgroups,including gestational hypertension group (30 cases),mild preeclampsia group(30 cases) and severe preeclampsia group(30 cases).A totally of 30 cases of healthy pregnant women were defined as the control group.All of them were admitted to Xuzhou Maternity and Child Health Care Hospital from August 2011 to December 2012.ELISA was used to detect the expression of HSP70 in maternal serum and umbilical cord blood.Immunohistochemistry streptavidin peroxidase(SP) was used to detect the protein in placenta,and semi-quantitative reverse transcription (RT)-PCR was used to detect the expression of HSP70 mRNA.Results (1) The levels of HSP70 in maternal serum and cord blood of mild preeclampsia group were (2.61±0.98) and (0.78±0.27)μg/L,respectively; and were (3.10± 1.18) and (0.96±0.28)μg/L in severe preeclampsia group.The levels of HSP70 in mild and severe preeclampsia groups were significantly higher than those in the control group [(1.88±0.79) and (0.61±0.15) μg/L,respectively] and gestational hypertension group [(2.13 ± 0.71) and (0.64 ± 0.18) μg/L,respectively;P＜0.05].The level of HSP70 in severe preeclampsia group was significantly higher than that in mild preeclampsia group (P＜0.05).And the level of HSP70 in gestational hypertension group was higher than that in the control group,but there was no statistical difference (P＞0.05).(2)The positive rate of placental HSP70 in gestational hypertension group,mild and severe preeclampsia group [83％(25/30),90％ (27/30) and 100％(30/30)],respectively were significantly higher than those in the control group(43％,13/30;P＜0.05).The positive rate of placental HSP70 in severe preeclampsia group was significantly higher than that in gestational hypertension group and mild preeclampsia group(P＜0.05).(3)The expression of placental HSP70 mRNA in gestational hypertension group,mild and severe preeclampsia group (0.82±0.27,0.92± 0.26 and 1.36±0.29,respectively) were significantly higher than that in the control group (0.45±0.18),with statistically significant differences (P＜0.05).The expression of placental HSP70 mRNA in severe preeclampsia group was significantly higher than that in gestational hypertension group and mild preeclampsia group(P＜0.05).Conclusion The expression of HSP70 increased significantly in maternal serum,umbilical cord blood and placenta of patients with HDCP,and it had positive correlation with the severity of the disease,indicating that HSP70 may play a role in the pathogenesis of HDCP.