Objective: The purpose of this study was to compare 2- dimensional and 3- dimensional power- Doppler imaging diagnostic performance for the prediction of ovarian cancer in complex adnexal masses. Study design: Sixty- nine complex adnexal masses in 60 women (mean age, 48.4 years [range, 17- 82 years]) were evaluated by 2- dimensional and 3- dimensional power- Doppler imaging for differentiating benign from malignant masses. Complex adnexal mass was defined in the presence of at least 1 of the following features: solid areas, thick papillary projections, thick septa, or purely solid echogenicity. One examiner performed 2- dimensional power- Doppler imaging, and a second examiner performed 3- dimensional power- Doppler imaging. All masses were removed surgically, and definitive diagnosis was obtained. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated for both techniques. Results: Forty- five tumors (65.2% ) were proved to be malignant, and 24 tumors (34.8% ) were proved to be benign. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for 2- dimensional power- Doppler imaging were 97.8% , 87.5% , 93.6% , 95.5% , and 94.2% , respectively. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for 3- dimensional power- Doppler imaging were 97.8% , 79.2% , 89.9% , 95% , and 91.3 % respectively. There were no statistical differences in sensitivity and specificity (McNemar test: P =. 250) Conclusion: Three- dimensional power- Doppler imaging did not have a better diagnostic performance than 2- dimensional power- Doppler imaging for the discrimination of benign from malignant complex adnexal masses. Objective: The purpose of this study was to compare 2-dimensional and 3- dimensional power-Doppler imaging diagnostic performance for the prediction of ovarian cancer in complex adnexal masses. Study design: Sixty-nine complex adnexal masses in 60 women (mean age, 48.4 years [range, 17-82 years]) were evaluated by 2-dimensional and 3- dimensional power-Doppler imaging for differentiating benign from malignant masses. Complex adnexal mass was defined in the presence of at least 1 of the following features: solid areas, thick papillary projections, thick septa, or purely solid echogenicity. One examiner performed 2-dimensional power-Doppler imaging, and a second examiner performed 3- dimensional power-Doppler imaging. All masses were removed surgically, and definitive diagnosis was obtained. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated to both techniques. Results: Forty-five tumors (65.2%) were proved to be malig Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for 2-dimensional power-Doppler imaging were 97.8%, 87.5%, 93.6%, 95.5% and 94.2%, respectively. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for 3-dimensional power-Doppler imaging were 97.8%, 79.2%, 89.9%, 95%, and 91.3% respectively. Differences in sensitivity and specificity (McNemar test: P =. 250) Conclusion: Three-dimensional power-Doppler imaging did not have a better diagnostic performance than 2-dimensional power-Doppler imaging for the discrimination of benign from malignant complex adnexal masses.