The renal arteries are paired blood vessels that branch from the abdominal aorta to supply each kidney with oxygenated blood. The right renal artery passes behind the inferior vena cava to reach the right kidney, while the left renal artery takes a shorter course to the left kidney. On Doppler ultrasound, the renal arteries are evaluated for stenosis (narrowing), which is an important cause of secondary hypertension and progressive kidney disease. Elevated peak systolic velocities and abnormal renal-to-aortic ratios suggest significant stenosis. Sonographers also assess the intrarenal arterial waveforms — a dampened waveform pattern in the kidney (the “tardus parvus” pattern) can indicate upstream stenosis. Renal artery evaluation requires careful technique and patient preparation to overcome challenges from overlying bowel gas.