Abstract: Objective : To elucidate the role of E-cadherin and nm23 gene in the pathogenesis and developing of gestational trophoblastic disease. Methods : Immunochemistry, 24 cases of non-ma-lignant transforming mole, along with 15 cases invasive mole, 15 cases of choriocarcinoma, 18 cases of first-trim ester placentas were investigated. Results : First-trim ester placentas were more often E-cad-herin-strongly-positive than invasive mole and choriocarcinoma, (P<0.01), and so in hydatidiform mole (P<0.05). The expression of nm23-H₁ in first-trim ester placentas was significantly higher than in malig-nant trophoblastic disease(P<0.01). In hydatidiform mole, nm23-H₁ expression was significantly higher than in invasive m ole(P<0.01) and choriocarcinoma (P<0.05). The expression of E-cadherin positively correlated with the expression of nm23-H₁ in both hydatidiform mole and malignant trophoblast disease. Conclusions : The expression of E-cadherin and nm23-H₁ were correlated with the invasiveness of trophoblast, and maybe it can be a predictor of prognosis of hydatidiform mole. Cytotrophoblast play a more important role than syncytiotrophoblast during invasiveness and metastasis.