Abstract: Objective: To determine the expressions of ERα and ERβ in endometrial carcinoma and to investigate their correlation with the prognosis.Methods: The expressions of ERα and ERβ in 36 normal endometria and 62 endometrial carcinomas were determined by immunohistochemical staining S-P method,and their association with the prognosis of endometrial carcinoma was analyzed.Results: The positive expression of ERα in endometrial carcinoma was 29.0%,which was significantly lower than that in normal endometria(83.3%) (P<0.01);the expression of ERβ was 22.6% and 27.8% in endometrial carcinoma and normal endometria,respectively.The difference was not significant(P>0.05).The expression of ERα in endometrial carcinoma was significantly associated with the surgical stage,differentiation and lymphatic invasion(P<0.05).Conclusions: ERα plays an important role in the genesis and development of endometrial carcinoma,and low expression of ERα may indicate poor prognosis.