Objective: To investigate the efficiency of helical CT comparing with contrast-enhanced ultrasound, and to improve the diagnosis efficiency of renal cell carcinoma(RCC).Methods: Thirty RCCs confirmed pathologically were studied retrospectively.The un-enhanced CT scan and the triphasic enhanced helical CT scan were performed in all cases, the gray-scale US and angiosonography with SonoVue were performed in all cases meantime.Results: 22 cases(73.3%)were diagnosed correctly by helical CT alone before operation.7 cases(23.3%)were suspected as RCC with helical CT.One case (3.3%)was misdiagnosed with helical CT.25 cases(83.3%)were diagnosed correctly with contrast-enhanced ultrasound alone pre-operation.One case(3.3%)was suspected as RCC with angiosonography.Four cases(13.3%)were misdiagnosed with angiosonography alone.29 cases(96.7%)were diagnosed correctly by helical CT combining with angiosonography before operation, one case(3.3%)was diagnosed as renal mass with both helical CT and angiosonography.Conclusion: Contrast-enhanced ultrasound is sensitive in detecting blood flow, it can detect the enhancement of the tumor which cannot be detected by helical CT.CT and angiosonography have strong complement each other in the diagnosis of RCC.