Qianying Zhao,1,* Ting Gui,1,* Qiuhong Qian,1,2 Lei Li,1 Keng Shen1 1Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 2Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Shandong, People’s Republic of China *These authors contributed equally to this work Abstract: Epithelial ovarian cancer, a vexing challenge for clinical management, still lacks biomarkers for early diagnosis, precise stratification, and prognostic evaluation of patients. B-cell-specific Moloney murine leukemia virus integration site 1 (BMI1), a member of the polycomb group of proteins, engages in diverse cellular processes, including proliferation, differentiation, senescence, and stem cell renewal. In addition, BMI1, as a cancer stem-cell marker, participates in tumorigenesis through various pathways. Rewardingly, recent studies have also revealed a relationship between BMI1 expression and the clinical grade/stage, therapy response, and survival outcome in a majority of human malignancies, including epithelial ovarian cancer. Therefore, BMI1 might serve as a potential stratification factor and treatment target for epithelial ovarian cancer, pending evidence from further investigations. Keywords: B-cell-specific Moloney murine leukemia virus integration site 1 (BMI1), epithelial ovarian cancer (EOC), molecular marker, treatment target, cancer stem-cell, tumor heterogeneity