Abstract: Objective: To explore the relations between the expression of claudin-1 and claudin-4 in endomentrial carcinoma and the clinicopathologic parameters.Methods: The expressions of claudin-1 and claudin-4 were determined in 52 cases of endometrial carcinomas,24 cases of dysplasias and 19 cases of proliferative endometriums by S-P immunohistochemistry,and their correlations to the clinicopathologic parameters were analyzed.Results: The positive expression rates of claudin-1 in proliferative endometrium,endometrial dysplasia and endometrial carcinoma were 89.5%,66.7% and 63.5%,respectively,with a trend of decreasing.The difference was significant in the three groups(P<0.005).The positive expression rates of claudin-4 in the above groups were 36.8%,70.8% and 90.4% respectively,with a trend of increasing.There difference was significant in the three groups(P<0.005).The expression of claudin-1 had no correlation to the histological grade,pathologic stage,myometrial invasion,lymph node metastasis or histological type;while the expression of claudin-4 was related to the myometrial invasion,but had no relation to the above parameters.Conclusions: Hypoexpression of claudin-1 and overexpression of claudin-4 may be involved in the carcinogenesis and development of endometrial carcinoma,and may contribute to the diagnosis,treatment and prognosis of endometrial carcinoma.