Objective: To determine the role of 3-Dimensional Ultrasound (3-D) and Power Doppler (3-DPD) in the diagnosis of ovarian tumors and to examine the diagnostic accuracy of this new ultrasonographic technique in the detection of ovarian cancer. Methods: A preoperative analysis by 3-D and 3-DPD was performed between November 2003 and November 2006 of 318 women referred for the evaluation of a unilateral ovarian mass within the first Department of Obstetrics and Gynecology, University of Athens, in Alexandra Hospital. The age of the women studied was 47,418,8 years with a range (18-72 years). Three dimensional ultrasonographic method is a new diagnostic technique that provides precise and additional information of the region of interest by the rotation of the mechanical transducer through 360ο. Multiple sections of the ovarian tumor, rotation in the three axis (x, y, z), translation and reconstruction of (3-D) plastic images allow more meticulous and detailed evaluation, especially when modes used. Comprehensive (3-D) display allows interactive qualitative and quantitative analysis of the tumor microcirculation in three dimensions. In the present study, were analyzed sonomorphological criteria (wall structure, shadowing, septa <3mm, solid parts, echogenicity, the existence of peritoneal fluid, the relationship with surrounding structure and 3 criteria by (3-DPD) [Vessel’s architecture, branching pattern and tumoral blood flow (R.I.)], based on Kurjak’s scoring system. When it was necessary some patients were evaluated more detailed with imaging techniques (CT scan, M.R.I.), tumor markers, and at last were noted the family and personal history and analyzed demographic considerations. All of the women were operated and comparison of the ultrasound findings with the histopathological diagnosis was conducted. The malignant ovarian tumors were classified according to the International Federation of Gynecologists and Obstetricians (F.I.G.O). Statistical analysis: The diagnostic accuracy of 3-D ultrasound was estimated by R.O.C. curve and for statistical analysis of the data, was used the x²-test. Results: In the present study was included the largest number of patients (318 women) according to international literature. The women that were in reproductive age were examined independently of the phase of their menstrual cycle (proliferative or secretory) thus providing a more objective result. The histopathological diagnoses were 225 benign ovarian tumors and 93 malignant. The combined use of 3-D and 3-DPD was showed 215 benign and 103 malignant ovarian tumors. A cut off value of 6 was used for the discrimination of benign and malignant tumors based on a specific scoring system concerning 3-D ultrasonographic criteria. The sonographic appearance of a malignant ovarian tumor as characterized by 3-D and 3-DPD was: papillary protrusions, septa abnormal surface, abnormal echogenicity and vascularity in the centre or at the periphery with abnormal branching pattern, scattered vessels and vascular shunts. Three dimensional methods diagnosed 6 malignant tumors as benign (false negative) and 16 benign ovarian tumors as malignant (false positive). The combined morphologic and three dimensional Power Doppler examination of ovarian tumors reached sensitivity and specificity 93,5% and 92,9% respectively while P.P.V. was 84,5% and N.P.V. was 97,2%. The 3-D ultrasound analysis with high score (>6) was associated with malignant histopathological types, with older women (54,7±10,5 years) with low social economical level (p=0,0034), with family history (p=0,999), with more than two coffees per day, with a history of breast cancer (p=0,010) and with hypertension (p=0,017). It has also to be reported that was a statistical significance between clinical symptoms and the high score of 3-D ultrasonographic criteria (p<0,001). C.T. was also statistically correlated with ovarian malignancy (p<0,001). Serum cancer markers such as Ca125, CEA, Ca15-3 were statistically correlated with high score (>6), indicative of ovarian malignancy (p<0,001). In the present study was also proved a statistically significance between high score and the stage of ovarian cancer (p>0,027), the probability of metastatic disease and the grade (borderline correlation: p=0,078). Conclusions: Even if color transvaginal ultrasonographic method has been established as a worthy and effective technique in the estimation of ovarian neoplasms has the disadvantage not to view the ovarian lesion entirely. On the contrary, 3-D sonographic analysis has the advantage of precise location, and measurement of ovarian tumor and allows multiplanar presentation of the capsule infiltration for the meticulous estimation of the ovarian lesion and at last, 3-D imaging shows abnormalities of neovascularization vessels with small diameter (<1mm) for the study of ovarian’s tumor microcirculation. The advantages, of the combined use of 3-D and 3-DPD are: 1. Objective diagnosis of ovarian neoplasms and discrimination of them in benign-malignant in order to reduce false negative and false positive results. 2. The contribution of this ultrasonographic method in the diagnosis of early stage I ovarian cancer. 3. The reduction of examination’s time and patient’s discomfort. Three dimensional ultrasound is a new emerging technology with a high level of diagnostic accuracy and main purpose the significant reduction of morbidity and mortality of ovarian cancer.