PURPOSE: To assess the differences between imaging findings of mucinous and serous cystadenocarcinomas of the ova r y, as seen on computed tomography (CT). MATERIALS AND METHODS: The CT findings of 24 patients with mucinous cystadenocarcinoma (25 tumors) and 26 with serous cystadenocarcinoma (47 tumors) of the ovary were retrospectively analysed. Images were evaluated for tumor size, contour, CT attenuation of locules within the mass, the presence of septal vegetation, the proportion of solid portion within the mass, the presence of calcification, and carcinomatosis peritonei. RESULTS: Mucinous cystadenocarcinomas tend to have a smooth contour (96%), variable CT attenuation of locules (80 %), and even size of locules within the mass (88.0%). Serous cystadenocarcinomas, on the other hand, tend to have an rregular lobulated contour (89.4 %), unevenly sized locules (76.6%), septal vegetation (57.4 %), and a prominent solid portion (59.6%). Bilaterality and carcinomatosis peritonei were more common in serous than in mucinous cystadenocarcinoma. CONCLUSION: Features which are valuable for the differentiation of mucinous and serous cystadenocarcinomas of the ova r y, as seen on CT, are tumor size, contour, varying locule attenuation and size, septal vegetation, a solid portion, bilaterality and peritoneal seeding.