Objective To detect the expression of aquaporins-8 ( AQP-8 ) in placenta and fetal membrane tissue of pregnant women with hypertensive disorders ,and to explore the role of AQP-8 in the pathogenesis of gesta-tional hypertension .Methods 81 term pregnant women with cesarean section were selected ( including 25 cases hypertensive disorders complicating pregnancy,26 cases with preeclampsia,30 cases with normal pregnancy),immu-nohistochemical method was used to detect AQP-8 expression in placenta ,fetal membranes tissue of those 3 groups. Results AQP-8 protein expressed in placenta ,fetal membranes of pregnant women in 3 groups.Mainly in epithelial cells of the amnion , chorionic trophoblast nucleus , syncytiotrophoblast membrane and cytoplasm of placenta .The expression levels of AQP-8 in the amnion of the control group , hypertension group and preeclampsia group were (4.78 ±2.05),(5.45 ±2.08),(6.18 ±2.15),respectively.Those levels in the chorion of three groups were (4.16 ±2.13),(5.04 ±1.92),(5.59 ±2.39),respectively.Those levels in the placenta of three groups were (5.62 ±2.16),(6.01 ±2.30),(7.61 ±2.71),respectively.Expression of AQP-8 protein was gradually increased , and had statistical differences in different places (F=3.121,3.148,5.785,P=0.049,0.048,0.005).The difference of AQP-8 protein expression in amnion of normal group and preeclampsia group was statistically significant (t=2.01, P=0.016).Conclusion Expression of AQP8 protein in placenta and fetal membranes of pregnant women with hypertensive disorder was significantly increased ,and was associated with severity of disease ,it might be involved in the occurrence and development of gestational hypertension . Key words: Hypertension, pregnancy-induced ; Aquaporins-8 ; Placenta