Objective: Evaluate the usefulness of the Malignancy Risk Index II (MRI II) using diagnostic accuracy variables in 100 patients diagnosed with adnexal mass. Method: In a sample of 100 patients with a diagnosis of adnexal mass, demographic variables were quantified, and MRI II was applied. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were obtained using a 2 x 2 table and compared with the histopathological result. Results: MRI II with a positive result was presented in 73.1% (52 patients) with malignant histopathological result and in 26.9% of patients with benign histopathological result. It presents a sensitivity in the test of 73.1%, a specificity of 70.8%, positive and negative predictive value of 73.2 and 70.8%, respectively. Diagnostic accuracy of 72%. Conclusions: MRI II is a screening tool with acceptable diagnostic performance to regulate behavior, such as referring to a specialized center or requesting more specific studies in patients diagnosed with adnexal mass due to suspected malignancy.