Objective. To compare gray scale and color Doppler features of primary and metastatic ovarian carcinomas. Methods. Clinical, sonographic (gray scale and color Doppler), and histopathologic data of 143 patients with primary (n = 127 adnexal masses) and metastatic (n = 34 adnexal masses) ovarian cancer were reviewed. Morphologic gray scale parameters assessed were bilaterality, tumor volume, echogenicity, and presence of septa, papillary projections, or solid areas. Color Doppler parameters were presence of blood flow, tumor blood flow location (central versus peripheral), subjective impression of blood flow amount (scanty, moderate, or abundant), lowest resistive index, lowest pulsatility index, and maximal peak systolic velocity (centimeters per second). Results. No statistical differences were found in bilaterality, tumor volume, presence of septa, papillary projections or solid areas, presence of blood flow, tumor blood flow location, subjective impression of blood flow amount, lowest resistive index, lowest pulsatility index, and maximal peak systolic velocity. Metastatic carcinomas were more frequently purely solid tumors (47% versus 26%; P = .001; likelihood ratio, 2.4; 95% confidence interval, 1.2-4.7). Conclusions. The presence of a purely solid tumor indicates a higher probability of metastatic carcinoma than primary ovarian cancer. However, with the use of gray scale and color Doppler sonography, it is difficult to differentiate primary ovarian carcinomas from metastatic tumors to the ovary. Key words: color Doppler sonography; metastatic cancer; ovarian cancer; sonography.Received September 20, 2002, hen an ovarian tumor is identified as questionable at sonographic examination, primary ovarian cancer should be the main concern. However, about 5% to 30% of malignant ovarian tumors are metastatic tumors to the ovary. 1 The preoperative distinction between primary ovarian cancers and metastatic lesions might be of clinical relevance, because surgery is of the utmost importance in the treatment of primary ovarian cancer, given that optimal cytoreduction and accurate surgical staging are 2 of the most important prognostic factors in this disease. 2,3 However, this surgical effort in metastatic cancers to the ovary might not be worthwhile. 4