Objective： To analyze the CT findings of renal masses and to investigate the value of CT imaging in qualitative diagnosis of these diseases. Methods： Twenty-eight cases of renal masses, proven surgically and pathologically, were retrospectively analyzed. Pre- and post-contrast CT scans were performed in all cases. Results： Twenty-one of 28 cases （75%） were diagnosed as having malignant tumors with 16 cases of renal cell carcinoma （RCC） showing as irregular-shaped low density soft tissue mass with no or slight enhancement. Ten of 21 cases were diagnosed as having carcinoma of the renal pelvis showing as soft tissue mass in renal pelvis with no or slight enhancement. Three of 21 cases were diagnosed as having nephroblastoma （Wilms＇ tumor） showing as larger irregular lobucated mass with no enhancement. Three of 28 cases （11%） of benign tumors were diagnosed as having angiomyolipoma （AML）. Two cases showed a mixed density mass while another case showed iso-density mass. The soft tissue part of the tumor showed enhancement while the area of fat didn＇t show any enhancement of the contrast medium. Four of 28 （14%） included 3 cases of renal cysts showing as classic cystic lesions with clear-margin. No enhancement was found. In the remaining one case of renal abscess, CT showed a mixed density mass of soft tissue and cyst with slight enhancement of soft tissue part while no enhancement of cystic part. Conclusion： Pre-contrast and post-contrast CT scans in combination with history play an important role in the diagnosis of renal
