Abstract: Objective To investigate the expression of activating transcription factor 5 (ATF5) in endometrial carcinoma and its clinical significance.Methods The expression of ATF5 in endometrial cancer and its relation with prognosis was analyzed by bioinformatics. Immunohistochemistry was used to detect the levels of ATF5 protein in endometrial carcinoma, endometrial hyperplasia and normal proliferative endometrial tissues. Kaplan-Meier survival analysis was performed to compare the overall survival of patients with different ATF5 protein levels and to analyze their relationship with the clinicopathological characteristics of endometrial cancer patients.Results The mRNA expression of ATF5 significantly increased in endometrial carcinoma tissue (P<0.05). Immunohistochemical results showed that ATF5 protein levels in endometrial carcinoma tissue were significantly higher than those in endometrial hyperplasia and normal proliferative endometrial tissues (P<0.05). The expression of ATF5 protein was related with age, differentiation and clinical stage (P<0.05). Multivariate Cox regression analysis showed that age, clinical stage and ATF5 protein expression were the independent risk factors for the overall survival of endometrial cancer patients(P<0.05). Kaplan-Meier survival analysis showed that endometrial cancer patients with high ATF5 expression had a significantly lower 5-year survival rate than those with low ATF5 expression (P<0.05).Conclusions The expression of ATF5 is up-regulated in endometrial carcinoma and closely related to age, differentiation, clinical stage and prognosis.