Introduction: Precise risk assessment of adnexal masses preoperatively is important for early diagnosis and better prognosis of ovarian malignancy. Although, there are many models for the prediction of ovarian malignancy, risk of malignancy index-1 (RMI-1) and International Ovarian Tumor Analysis-Simple Rules (IOTA-SR) are the most used. The aim of our study was to compare the diagnostic accuracy of IOTA-SR with RMI-1 for preoperative differentiation of benign and malignant adnexal masses. Materials and methods: A total of 121 women with adnexal masses, planned for surgery were enrolled in the study. Serum CA-125 was done, and an ultrasound examination was performed at the time of preoperative assessment by consultants. RMI-1 score of more than 200 was the cut-off value used to denote malignancy. IOTA-SR was applied to find the nature of the mass. Based on the histopathology report the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. The diagnostic accuracy of RMI-1 and IOTA-SR were compared. Results: The study included 121 adnexal masses, out of which 110 (90.9%) were benign, 8 (6.6%) were malignant and 3 (2.5%) were borderline ovarian tumors. About 22.3% of the cases were found to be inconclusive by IOTA-SR. Sensitivity, specificity, PPV, and NPV of RMI-1 were 63.6, 100, 100, and 96.4%, respectively, whereas that of IOTA-SR was 100, 96.4, 73.3, and 100%, respectively. The diagnostic accuracy of IOTA-SR was better than RMI-1 (AUC = 0.98 vs 0.87). Conclusion: The model, IOTA-SR, for the prediction of ovarian malignancy, has better diagnostic accuracy and higher sensitivity when compared to RMI-1 in preoperative discrimination of benign and malignant adnexal mass.