Background: Ovarian cancer is one of the causes of death in women, and in about 70% of cases is recognized only in advanced stages. This study was undertaken to evaluate distinctive values of transvaginal and color Doppler ultrasonography in differentia­ting malignant and benign adnexal masses through analysis of ultrasonic morphological features of malignancy and estimation of location and intensification of angiogenesis as well as values of resistance of flow in examined masses. Patients and methods: 329 women with malignant and benign adnexal masses underwent ultrasonographic and colour Doppler examination 1-5 days before surgery (laparotomy, laparoscopy) thus allowing histological verification of diagnosis. The ultrasono-graph.ic structure was assessed using a morphological scoring system devised by Sassone [4], Jain [5] and Benacerraf [6]．Regions showing vasculature, especially within septae and solid parts of tumours were examined by means of transvaginal colour Doppler. Location and intensification of angiogenesis as well as resistance index (RI) were investigated. Sensitivity, specificity, PPV and NPV of both techniques were assessed. Statistical analysis of obtained data were based on the Student' s t test; p < 0.05 level was considered significant. Results: Postoperatively 255 (77.5%) benign and 74 (22.5%) malignant tumours were seen. In the group of benign masses the average age of women was 42.6 ± 12.3 and in the malignant it was 53.1 ± 12.6 (p < 0.0001). The transverse dimension of benign lesions was 77.2 ± 19, whereas for malignant it was 107.0 ± 1 (p < 0.0001). Benign tumours in 63.0% were cystic, in 26.0% mixed cystic­solid and in 11.0% solid echostructures while in malignant they were respectively, 6.8%, 56.8% and 36.4% (p < 0.0001). Doppler flow within the tumour was 74.5% in benign and 98.6% in malignant masses (p <0.0001). In benign lesions homogenous superficial or peripheral vasculature was visualized, and in the majority of cases (82.7%) it was of medium intensification. However in malignant central, peripheral or mixed vascularisation, in the majority intensified character was found. Average value of the resis­tance index in all benign masses amounted to 0.77 ± 0.14, however in malignant it was 0.39 ± 0.07 (p < 0.0001). Conclusions: We contend that complete ultrasonographic estimation of ovarian neoplasms outside the qualification of structural details should include Doppler analysis of vasculature parameters. Most important is the qualification of resistance of flow, and loca­tion and intensification of vascularisation in examined masses which permit the differentiation of malignant and benign lesions. Preoperatively recognizing malignant processes with colour Doppler ultrasonography shows higher accuracy, specificity and PPV.