Purpose:To find a valuable index for the qualitative diagnosis of renal tumor by color doppleranalysis. Methods :The arteriorenal blood flow of 32 patients with renal tumor and 30 healthy person were inves-tigated by color doppler analysis. Results:The arteriorenal systolie peak flow velocity of malignant tumor groupwas higher than that of the benign tumor group and the control group ( P ＜0. 01 ); but the resistance index of themalignant tumor group was lower than that of the other two groups ( P ＜0.01). There was no significant differ-ence between the benign tumor group and the control group in arteriorenal peak flow velocity and resistance in-dex. Conclusions :The increase of arteriorenal systolie peak flow velocity and the decrease of resistance index wereconsidered to be a valuable index for the qualitative diagnosis of malignant renal tumor.