An endometrioid carcinoma coexisting with choriocarcinomatous differentiation is an uncommon event with an aggressive clinical course and a poor prognosis. The authors describe an endometrioid carcinoma of the endometrium provided with a focus of choriocarcinoma-like cells in a 50-year-old menstruated woman with a history of abnormal uterine bleeding. A total bilateral hystero-annessectomy was performed. Histopathologic study showed endometrioid adenocarcinoma limited to the endometrium with a single microinvasive (< one mm) choriocarcinomatous focus. Immunohistochemistry established intense reactivity of tumor cells for CK 7 and AE1/AE3, for beta-human chorionic gonadotropin (beta-hCG), and for HER2 confirming the diagnosis. During the clinical course and follow-up, serum levels of beta-hCG were always negative. Up to date the patient is still alive with no evidence of disease. Even if endometrioid carcinoma with choriocarcinomatous differentiation is considered highly malignant, occasionally it may have a good prognosis, especially when a non-invasive behaviour is detected together with negative serum beta-hCG levels.