A choriocarcinomatous component is rarely present in carcinomas of certain sites and few cases of choriocarcinomatous differentiation in endometrioid adenocarcinoma have been reported. The present study reports a case of endometrioid adenocarcinoma of the uterine corpus with choriocarcinomatous differentiation, and discusses the clinicopathological features of this rare tumor. A 59-year-old post-menopausal female presented with abnormal vaginal bleeding. Magnetic resonance imaging demonstrated a relatively well-circumscribed tumor in the uterine corpus and a total cystectomy was subsequently performed. A histopathological examination revealed two distinct components in the uterine corpus tumor. The first component comprised ~80% of the tumor and was composed of poorly-differentiated endometrioid adenocarcinoma. The remaining component consisted of mononucleated and syncytial giant cells containing rich eosinophilic cytoplasm and large pleomorphic nuclei with coarse chromatin. An immunohistochemical analysis revealed that these syncytial giant cells were positive for β-human chorionic gonadotropin (hCG). Therefore, a diagnosis of endometrioid adenocarcinoma with choriocarcinomatous differentiation was confirmed. The clinicopathological features of nine previously reported cases of this tumor were analyzed in addition to the present case. The majority of the patients were post-menopausal. Endometrial choriocarcinoma may be considered to have a highly aggressive clinical course, since nine of the 10 cases displayed metastases and four patients succumbed to the disease. The pathogenesis of the choriocarcinomatous component is not well understood. However, genetic studies have demonstrated that conventional carcinoma and choriocarcinomatous components share common genetic alterations. The choriocarcinomatous component represents aberrant differentiation of the conventional carcinoma, however, genetic analyses of endometrioid adenocarcinoma with choriocarcinomatous differentiation have not been performed.