We collected surgically resected primary ovarian cancers of four major subtypes (high-grade serous carcinoma, mucinous carcinoma, endometrioid carcinoma and clear cell carcinoma), secondary ovarian tumors (e.g. colon cancer metastasized to the ovary) and their extraovarian lesions, and then analyzed the expression of FOXL2 by immunohistochemistry. The gene discussed is FOXL2; the disease is endometrioid adenocarcinoma.