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. © 2005 Elsevier Inc. All rights reserved.