Duplex Doppler sonography has been reported to be useful in examining the intrarenal hemodynamic abnormalities in various renal diseases. We investigated the impact of diabetes on intrarenal hemodynamics in patients with chronic renal failure (CRF). The resistive index and pulsatility index of the renal interlobar arteries were measured using duplex Doppler sonography in 90 CRF patients (serum creatinine >130 and <800 mmol/l, mean age 59 ± 11 years). Forty-eight patients had type 2 diabetes and 42 did not. Twenty-nine age-matched, healthy subjects served as controls. Both resistive index and pulsatility index were greater in CRF patients than in the controls (p < 0.0001). No significant differences existed in age, sex, body mass index, total serum cholesterol, serum creatinine, estimated creatinine clearance, or mean blood pressure between the diabetic CRF and nondiabetic CRF groups. Resistive index and pulsatility index were significantly increased in the diabetic CRF patients compared to the nondiabetic CRF patients (p < 0.0001). Multiple regression analysis of all CRF patients revealed that resistive index was independently affected by the presence of type 2 diabetes (F = 44.535), as well as decreased creatinine clearance (F = 18.157) and age (F = 15.160) (R<sup>2</sup> = 0.559, p < 0.0001). These results clearly demonstrated that intrarenal arterial resistance is significantly increased in CRF patients with type 2 diabetes compared to similar patients without diabetes. The impact of diabetes mellitus and advanced age on intrarenal hemodynamics may be due to intrarenal arteriosclerosis and interstitital lesions. Measurements of RI values in addition to conventional ultrasound imaging may add further information on such renal lesions.