BACKGROUND: Prediction of ovarian malignancy by ultrasonographic findings and patient age in the scenario of clinically suspected adnexal masses is a desirable goal. METHODS: Prospective evaluation of clinically suspected adnexal masses was performed with transvaginal ultrasound using real-time, Doppler velocimetry, and color-flow mapping. Continuous ultrasound variables included ovarian volume, the Sassone morphology scale, and Doppler determination of angle-corrected systole, diastole, and time-averaged velocity, in addition to patient age. The Doppler pulsatility index (PI), vessel location, presence of a diastolic notch, and echogenic predominance of the lesion, suggestive of dermoid, also were assessed. RESULTS: Of 244 women with follow-up, 214 had nonmalignant findings (85 of which were benign neoplasms), and 30 had malignant neoplasms. Age and all ultrasound continuous variables except systole were found to be statistically significant (P < 0.05) between patients with both malignant (N = 30) and nonmalignant masses (N = 214), as well as those with benign (N = 85) and malignant (N = 30) neoplasms. By adding the continuous measures (age [in years], ovarian volume [mL], and Sassone morphology scale [1-15]) and weighting other variables ([-10] x PI, central or septal location [+10], peripheral location [-10], and echogenic [-10]), a receiver operating characteristic curve was generated (area under the curve = 0.91), which was found to be discriminating, predictive, and able to replicate the more complex logistic regression model. Prediction of malignancy was generated from the population-based data of the current study. CONCLUSIONS: The Ovarian Tumor Index, which combines patient age with specific ultrasonographic markers, is an accurate method for predicting ovarian malignancy in the clinical scenario of suspected adnexal masses.