To evaluate the efficacy of the biphasic and triphasic dynamic multidedector computerized tomography (MDCT) in the preoperative prediction of histological subtypes of renal cell carcinoma (RCC). Materials and methods: The preoperative dynamic MDCT findings of 51 patients with renal mass who had undergone nephrectomy were reviewed retrospectively. Twenty-five of the patients had biphasic (portal and excretory) and 26 had triphasic (arterial, portal, and excretory) MDCT images. Tumor size, presence of calcification, tumor-aorta attenuation values in all phases and homogeneicity of the tumor were noted for every patient. In heterogeneous tumors, the minimum and maximum attenuation values were noted to determine the extent of heterogeneicity. These data were compared for histopathological subtypes of the tumors. Results: In 8 patients, calcifications were detected in the mass although there were no significant differences among tumor subtypes with regard to the presence of calcification. In 33 patients the tumor was hypervascular with 24 clear type and clear type RCC showed more prominent contrast enhancement than papillary RCC. The enhancement degree showed no significant difference among other tumor subtypes. Moreover, when biphasic and triphasic computed tomography (CT) findings were compared, the positive predictive value of triphasic CT in detecting hypervascular clear tumors was greater (17/18; 94.4% versus 7/11; 63.6%). Conclusion: The dynamic MDCT technique appears to be useful in preoperative evaluation of renal masses suspected of being malignant and may also provide information about the histopathological subtype of RCC. ; To evaluate the efficacy of the biphasic and triphasic dynamic multidedector computerized tomography (MDCT) in the preoperative prediction of histological subtypes of renal cell carcinoma (RCC). Materials and methods: The preoperative dynamic MDCT findings of 51 patients with renal mass who had undergone nephrectomy were reviewed retrospectively. Twenty-five of the patients had biphasic (portal and excretory) and 26 had triphasic (arterial, portal, and excretory) MDCT images. Tumor size, presence of calcification, tumor-aorta attenuation values in all phases and homogeneicity of the tumor were noted for every patient. In heterogeneous tumors, the minimum and maximum attenuation values were noted to determine the extent of heterogeneicity. These data were compared for histopathological subtypes of the tumors. Results: In 8 patients, calcifications were detected in the mass although there were no significant differences among tumor subtypes with regard to the presence of calcification. In 33 patients the tumor was hypervascular with 24 clear type and clear type RCC showed more prominent contrast enhancement than papillary RCC. The enhancement degree showed no significant difference among other tumor subtypes. Moreover, when biphasic and triphasic computed tomography (CT) findings were compared, the positive predictive value of triphasic CT in detecting hypervascular clear tumors was greater (17/18; 94.4% versus 7/11; 63.6%). Conclusion: The dynamic MDCT technique appears to be useful in preoperative evaluation of renal masses suspected of being malignant and may also provide information about the histopathological subtype of RCC.