β-catenin is a very unusual protein with multiple functions depending on its cellular localization. The β-catenin gene (CTNNB1) encodes for β-catenin and apart from its well-defined role in cellular adhesion,it is also a component of the Wnt signalling pathway. The Wnt/β-catenin pathway is involved in various normal cellular activities,including determination,proliferation,migration and differentiation in embryonic development and adult homeostasis. Deregulation or constitutive activation of the Wnt/β-catenin pathway may lead to cancer formation. Immunohistochemical expression of β-catenin in gynecologic tumor have been reported recently. In normal epithelia,immunoreactivity was strongly observed at the membrane,partially at cytoplasm,nuclear staining of β-catenin was rarely seen in normal cases; In ovarian carcinomas,β-catenin nuclear expression was found more commonly in endometrioid carcinomas,nuclear β-catenin staining seemed to be of prognostic importance; In endometrium carcinomas,β-catenin nuclear expression were more common in pure endometrioid tumors than in unendometrioid tumors,associated with favorable prognosis,the staining pattern was independent of the menopausal status; In synchronous primary cancers of the endometrium and ovary,activating mutations in β-catenin seemed to distinguish synchronous primary tumors from metastatic tumors. β-catenin is a very unusual protein with multiple functions depending on its cellular localization. The β-catenin gene (CTNNB1) encodes for β-catenin and apart from its well-defined role in cellular adhesion, it is also a component of the Wnt Signaling pathway. The Wnt / β-catenin pathway is involved in various normal cellular activities, including determination, proliferation, migration and differentiation in embryonic development and adult homeostasis. Deregulation or constitutive activation of the Wnt / β-catenin pathway may lead to cancer formation Immunohistochemical expression of β-catenin in gynecologic tumors have been reported recently. In normal epithelia, immunoreactivity was strongly observed at the membrane, partially at cytoplasm, nuclear staining of β-catenin was rarely seen in normal cases; In ovarian carcinomas, β- catenin nuclear expression was found more commonly in endometrioid carcinomas, nuclear β-catenin staining seemed to be of prognostic importance; In endometrium carcinomas, β-catenin nuclear expression were more common in pure endometrioid tumors than in unendometrioid tumors, associated with favorable prognosis, the staining pattern was independent of the menopausal status; In synchronous primary cancers of the endometrium and ovary, activating mutations in β-catenin seemed to distinguish synchronous primary tumors from metastatic tumors.