The kidneys play a central role in the regulation of blood pressure and are also one of the main culprits of arterial hypertension (HT). Renal ultrasound is a valuable diagnostic tool that can provide instant information at the bedside on possible underlying causes and consequences of HT. Its role in the screening for renal artery stenosis is well-known. However, renal ultrasound can also detect abnormalities in renal parenchyma, morphology, or the vascularization of the kidneys, and as such directly influence further diagnostic work-up and treatment. The significance of the renal resistive index and the place of renal ultrasound in the latest international guidelines on HT are reviewed in this article.