Renal artery stenosis is the most common cause of potentially curable secondary hypertension. For a long time, angiography has been considered the “gold standard” in screening for renal arterial occlusive disease, but it is expensive and invasive. Magnetic resonance angiography and spiral computed tomography are safer alternatives to angiography but are expensive and not widely available. Due to the fact that duplex scanning is noninvasive, it has been advocated since the early 1980s as a screening test for renal vascular disorders. Factors that make duplex ultrasound an attractive screening measure for renovascular disease are its safety, suitability for outpatient use, and low cost. However, the frequency of artery variants, lengthy examination time, and technically inadequate test conditions limit the use of the direct duplex ultrasound detection of renal artery stenosis. Advances in Doppler technology may alleviate some of the current problems related to examination of renal arteries. One such technique is the use of echo-enhancing agents, which increase Doppler signal strength and can improve the sensitivity and specificity in Doppler ultrasound detection of renal artery stenosis.