Background: It is important to remember that ovarian cancer is a frequent and potentially fatal disease. For the purpose of characterizing the imaging properties of adnexal masses, the Ovarian-Adnexal Reporting and Data System (O-RADS) Committee have been established. Objective: The aim of the current work was to evaluate the validity of O-RADS to diagnose adnexal masses utilizing pelvic ultrasound. Subjects and methods: This prospective cohort study included a total of 30 women having at least one adnexal mass detected by US, recruited from Department of radiodiagnosis, Zagazig University Hospitals.   Results: About 75.8% of the adnexal masses were benign and 24.2% were malignant. The most frequent benign lesion among patients who had O-RADS 2 or 3 was a hemorrhagic cyst. Only 2 patients with O-RADS 5 had benign lesions (mucinous cystadenoma and serous cystadenoma), while 5 patients had malignant lesions.Regarding only those adnexal masses classified as O-RADS 5 to predict adnexal masses malignancy, the O-RADS had a specificity, sensitivity, PPV, NPV and accuracy of 92%, 62.5%, 71.4%, 88.5%, and 84.8%, respectively. Considering combined O-RADS 4 and 5 as a malignancy predictor of adnexal masses, the specificity, sensitivity, PPV, NPV, and accuracy were 72%, 87.5%, 50%, 94.7%, and 75.8%, respectively. Conclusion: It could be concluded that the U/S O-RADS classification system is a great noninvasive diagnostic tool for suspected ovarian masses with high sensitivity in differentiating between benign and malignant neoplastic tumors.