Purpose of the study This study aimed to evaluate and compare the diagnostic accuracy of two ultrasound scoring systems, Assessment of Different Neoplasias in the Adnexa (ADNEX) Model and Gynecology Imaging Reporting and Data System (GI-RADS), for the preoperative assessment of adnexal masses taking histopathology as gold standard. Methods This analytical study assessed 60 patients of age > 14 years with adnexal masses, planned for surgery. Ultrasound assessment and risk categorization according to ADNEX and GI-RADS were performed 2-3 days prior to surgery. Histopathology was used as a reference standard for the calculation of validity of two ultrasound scoring systems for diagnosis of adnexal masses. Results Out of 60 women (mean age, 35.52 +/- 13.86 years; range, 16-70 years) with adnexal masses, 24 were malignant and 36 were benign. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for the ADNEX model were 87.50%, 91.7%, 87.50%, 91.7% and 90.0%, respectively. The sensitivity, specificity, PPV, NPV and accuracy of the GI-RADS category were 95.8%, 61.1%, 62.2%, 95.7% and 75.0%, respectively. The diagnostic performance of the ADNEX model was better as compared to GI-RADS in terms of specificity and positive predictive value with a significant difference (p < 0.05). The area under curve (AUC) was 0.957 and 0.919 for ADNEX and GI-RADS, respectively (p = 0.252). Conclusion Although both ADNEX and GI-RADS systems had satisfactory diagnostic performances and high negative predictive values, the ADNEX model showed better specificity and positive predictive value in comparison with GI-RADS.