Endometrial carcinoma is one of the most common malignancies of female genital tract. Well differentiated endometrioid carcinoma is histologically similar to complex atypical endometrial hyperplasia and sometimes it is difficult to differentiate between them. We hypothesis that the use of PTEN the tumor suppressor gene, PCNA a marker of proliferation and B-Catenin oncogene may be of value to differentiate well differentiated endometrioid carcinoma from complex atypical endometrial hyperplasia. Methods Immunohistochemical evaluation of PTEN, PCNA and B-Catenin was performed on 100 specimens including; 8 proliferative endometrium, 10 secretory endometrium, 10 simple endometrial hyperplasia, 10 complex typical endometrial hyperplasia, 30 complex atypical endometrial hyperplasia and 32 endometrioid adenocarcinoma. Immunostaining of cells was analyzed by arbitrary semiquantitative methods according to both slide's staining area and intensity of color reaction. Results: PTEN was expressed in 100% of proliferative endometrium, 0% of secretory endometrium, 60% of simple typical hyperplasia, 100% complex typical hyperplasia, 46.7% complex atypical hyperplasia and 37.5% endometrioid adenocarcinoma. There was significant difference in PTEN expression between complex atypical endometrial hyperplasia and endometrioid adenocarcinoma. PCNA was expressed in 50% of proliferative endometrium, 40% of secretory endometrium, 80% of simple endometrial hyperplasia, 100% of complex typical hyperplasia, (46.7%) of complex atypical hyperplasia and 87.5% of endometrioid adenocarcinoma. There was significant difference in PCNA expression between complex atypical endometrial hyperplasia and endometrioid adenocarcinoma