Abstract: Objective To explore the relationship between the level of serum adiponectin and placental matrix metalloproteinase 9 (MMP-9) in patients with gestational hypertension.Methods According to the severity of disease,145 patients with gestational hypertension were divided into mild gestational hypertension group (n =72) and severe gestational hypertension group (n =73),and 60 healthy pregnant women at the same time were selected as control group.The levels of serum adiponectin and MMP-9 expression were compared among three groups.Results Compared with control group,the levels of serum adiponectin in gestational hypertension groups decreased significantly (P ＜ 0.05).There was significant difference between gestational hypertension groups and control group in the positive rate of MMP-9 (P ＜ 0.05 or P ＜ 0.01).The positive rate of MMP-9 in severe gestational hypertension group was significantly lower than that in mild one and control group (P ＜0.01).The level of serum adiponectin was positively correlated with placental MMP-9 in the patients with gestational hypertension (r =0.71,P ＜ 0.05).Conclusion The decrease of serum adiponectin and the decreased expression of MMP-9 in placenta may promote the occurrence and development of gestational hypertension.