Objective To study expression and clinical significance of TGF-? 1 in the placenta of the patients with pregnancy-induced hypertension(PIH). Methods The SABC immunohistochemical method was performed to determine the location and intensity of TGF-? 1 expression in placental tissues of 64 patients with PIH and 20 normal pregnant women. Results TGF-? 1 expression was principally localized in the trophoblast and decidual cells. The expression level of TGF-? 1 in the trophoblasts and decidual cells significantly increased in the patients with PIH compared with the normal pregnant women, and elevated with the severity of PIH increased. A negative relation was found between the expression level of TGF-? 1 and the weight of placenta and neonate in the patients with PIH. Conclusion The elevated expression of TGF-? 1 in placenta leads to the deficiency of trophoblast cell invasion, which may be one of the pathogenic causes of PIH.