Background: Ovarian cancer, the fifth leading cause of cancer-related death in women, is a highly lethal disease among all gynecologic malignancies. Stem cells (SCs) are undifferentiated cells destined to replenish the pool of mature cells whenever needed. In recent years, accumulating data demonstrate that a small subset of cells exists within a tumor, termed cancer stem cells (CSC), responsible for cancer development and recurrence. CD133 is considered a CSC marker in several non-ovarian cancers including cancers of the colon, the lung, and the brain. Objective: To evaluate the expression of the stem cells marker CD133 in surface epithelial tumors of the ovary and its correlation with clinic-pathological parameters. Patients and methods: 60 cases, divided into 39 cases of serous tumors, 12 cases of mucinous tumors, 6 cases of endometrioid carcinoma, and 3 Brenner tumors from 2018 to 2020, were stained for CD133 antibodies by immunohistochemistry. All clinical data were obtained from patients reports. Results: CD133 expression was found in 84.62% of ovarian surface epithelial tumors and in 37.5% of borderline tumors. CD133 expression showed a significant correlation with histopathological subtypes: high-grade serous carcinoma and mucinous tumors (P= 0.001). Evaluation of CD133 in relation to other histopathological parameters: CD133 showed significant correlation with presence of psammoma bodies, and presence of necrosis (P= 0.049, and 0.005) respectively. Also, statistical evaluation of CD133 expression according to presence of lymphovascular emboli, peritoneal nodules, and infiltration to other organs showed high significance with (P= 0.001) similarly to all. Conclusion: CD133 expression could be a predictor of poor clinical outcome for patients with ovarian surface epithelial tumors as its expression was associated with high-grade serous carcinoma, necrosis, lympho-vascular emboli, and peritoneal nodules.