Objective To study the role of p16 and cyclin D 1 in the genesis and development of endometrial carcinoma.Methods 12 cases of normal endometrium,22 cases of proliferative endometrium and 41 cases of endometrial carcinoma were detected for the expression of p16 and cyclin D 1 by means of immunohistochemical S P. Results In normal endometrium p16 was expressed while cyclin D 1 was almost negative in the proliferative phase,but both of them were negative in the secretory phase.Among the groups of the simple and compound hyperplasia, the atypical hyperplasia and the endometrial carcinoma,the expression of p16 showed a descending tendency, while the expression of cyclin D 1 showed an ascending tendency.In endometrial carcinomas the expression of p16 was significantly lower than that of normal endometrium and proliferative endometrium( P <0.01, P <0.05).However, the expression of cyclin D 1 in proliferate endometrium and endometrial carcinoma was significantly higher than that in normal endometrium ( P<0.05,P<0.01) .The overexpression of cyclin D 1 in the atypical hyperplasia group was obviously different from that in the simple and compound hyperplasia group ( P <0.01).In endometrial carcinoma,the expression of p16 was decreasing with the descending of cell differentiate degree, on the opposite, the expression of cyclin D 1 was increased and there existed a negative correlation between them.It was also observed that the overexpression of cyclin D 1 was significant different between G 1 and G 2,G 3(P<0.01).Conclusion p16 is a negative regulating factor of cell cycle in endometrial carcinoma, while cyclin D 1 is a positive one.Both of them are important in the genesis and development of endometrial carcinoma.The low expression of p16 and the overexpression of cyclin D 1 are related with the malicious biological behaviors of endometrial carcinoma and maybe play an important role in the judgement of prognosis.Overexpression of cyclin D 1 may be an earlier molecular event in the genesis of endometrial carcinoma. Objective To study the role of p16 and cyclin D 1 in the genesis and development of endometrial carcinoma. Methods 12 cases of normal endometrium, 22 cases of proliferative endometrium and 41 cases of endometrial carcinoma were detected for the expression of p16 and cyclin D1 by means of immunohistochemical S P. Results In normal endometrium p16 was expressed while cyclin D1 was almost negative in the proliferative phase, but both of them were negative in the secretory phase. Among the groups of the simple and compound hyperplasia, the atypical hyperplasia and the expression of p16 showed a descending tendency, while the expression of cyclin D 1 showed an ascending tendency. In endometrial carcinomas the expression of p16 was significantly lower than that of normal endometrium and proliferative endometrium (P <0.01, P < However, the expression of cyclin D1 in proliferate endometrium and endometrial carcinoma was significantly higher than that in normal endometrium (P <0.05, P <0.01). The overexpression of cyclin D 1 in the atypical hyperplasia group was obviously different from that in simple and compound hyperplasia group (P <0.01) .In endometrial carcinoma, the expression of p16 was decreased with the descending of cell differentiate degree, on the opposite, the expression of cyclin D1 was increased and there existed a negative correlation between them. It was also observed that the overexpression of cyclin D1 was significantly different between G1 and G 2, G 3 (P <0.01) .Conclusion p16 is a negative regulating factor of cell cycle in endometrial carcinoma, while cyclin D 1 is a positive one.Both of them are important in the genesis and development of endometrial carcinoma. low expression of p16 and the overexpression of cyclin D 1 are related with the malicious biological behaviors of endometrial carcinoma and maybe play an important role in the judgment of prognosis. Overexpression of cyclin D 1 m ay be an earlier molecular event in the genesis of endometrial carcinoma.