The preoperative diagnosis of ectopic ovarian tissue has been reported only once in the literature. In the present case, differential ovarian and adrenal testing was used to diagnose and aberrant ovarian source of persistently elevated plasma estrogen in a patient who had undergone bilateral oophorectomy and adrenalectomy for metastatic breast carcinoma. The ovarian source was diagnosed by stimulation with human chorionic gonadotropin (hCG), and treatment with human menopausal gonadotropin (hMG) prior to surgery was used to facilitate its location at laparotomy.