<b>Objective:</b> Incidence of renal cell carcinoma (RCC) in patients with end-stage renal disease (ESRD) is higher than in the general population. It is difficult to detect RCC in ESRD kidney using routine gray scaled ultrasonography (USG). The resistive index (RI) measured in the intra-tumor artery of RCC can be expected to be lower than the background parenchyma of the ESRD kidney due to their disorganized neovascularization. This study explored the usefulness of RI on spectral Doppler USG for detection of RCC in ESRD kidney. Materials and Methods: We identified 17 patients with ESRD kidneys in which renal masses were suspected on routine USG. They performed CT scans and additional Doppler USG for characterization of detected lesions. All underwent radical nephrectomy with the suspicion of RCC. 14 patients finally were included. RI measurements were done at the region of suspected renal mass and backgreround renal parenchyma. The intraclass correlation coefficient (ICC) was used to assess the reproducibility of RI measurement. The paired t-test was used to compare the RI values between the renal mass and background renal parenchyma (P < 0.05). Results: RI values measured at RCCs were significantly lower than those measured at background renal parenchymae (0.41~0.65 vs. 0.75~0.89) (P < 0.001). The intra-reader reproducibility proved to be excellent and good for the renal masses and parenchymae, respectively (P<0.001). Conclusion: RI on spectral Doppler ultrasonography is useful in detecting RCC in patients with ESRD. RI values measured at RCCs were significantly lower than those measured at background renal parenchymae.