Renal resistive index (RRI), which reflects intra-renal arterial impedance is routinely measured when undertaking renal Doppler ultrasonography (RDU). We investigated the relationship between elevated RRI and presence of chronic kidney disease (CKD), and examined whether elevated RRI at baseline is associated with decline in estimated glomerular filtration rate (eGFR) on follow-up. This retrospective observational study examined the association of elevated RRI (>0.7) with the presence of CKD (eGFR <60 mL/min for >3 months), demographic and clinical factors in multivariable models. We also examined the effect of elevated RRI on eGFR decline on follow-up using mixed models. Of the 346 patients undergoing RDU (median age 69.7 years, 46.2% male), 180 had elevated RRI. There was a strong inverse association between RRI and eGFR at baseline, 1 and 2 years (rho = -0.53, -0.51, -0.53, all p < 001). Elevated RRI was independently predicted by older age (Odds Ratio 3.29, 95% CI: 2.25-4.8, p < 0.001) and diabetes (Odds Ratio 2.65, 95% CI: 1.21-5.80, p = 0.015) but not CKD using multivariate logistic regression. Decline of eGFR was not different between RRI categories on follow-up. Elevated RRI was predicted by older age and diabetes, but not by the presence of CKD. Baseline RRI was not associated with eGFR decline. This article is protected by copyright. All rights reserved.