Background: Postmenopausal bleeding (PMB) is a common gynecologic complaint among elderly women, and endometrial hyperplasia is a common cause of this bleeding. Ovarian fibromas are the most common ovarian sex cord stromal tumors (SCST). They arise from non-functioning stroma, rarely show estrogenic activity, and stimulate endometrial hyperplasia, leading to abnormal vaginal bleeding. Case presentation: We report herein the case of a 64-year-old Chinese woman who presented with recurrent PMB. A sex-hormone test revealed her estrogen level was significantly higher than normal, and other causes of hyperestrogenism had been excluded. In the past 7 years, the patient had undergone four curettage-and-hysteroscopy procedures due to recurrent PMB and endometrial hyperplasia. Finally, the culprit behind the rise in estrogen – an ovarian cellular fibroma with estrogenic activity – was found in the fifth operation.Conclusions: Ovarian cellular fibromas occur insidiously, and some may have endocrine functions. For postmenopausal patients with recurrent PMB and endometrial thickening indicated by ultrasonography, it is recommended they undergo sex-hormone testing while waiting for results regarding the pathology of the endometrium. If the estrogen level remains elevated, even if the imaging does not indicate an ovarian tumor, the clinician should consider the possibility of an ovarian SCST and follow the patient closely. Once the tumor is found, no matter the size, it should be removed as soon as possible to avoid endometrial lesions caused by long-term estrogen stimulation. More studies are needed to confirm whether preventive total hysterectomy with bilateral salpingo-oophorectomy should be recommended for postmenopausal women with recurrent bleeding whose estrogen levels are higher than normal, even when the auxiliary examination does not indicate ovarian mass. It is possible this could avoid the physical and psychological burden caused by repeated curettage.