More than 72 million Americans have hypertension, and the majority of these persons have essential hypertension. However, a significant subset has a secondary cause. The most common cause of secondary hypertension is renal vascular hypertension, of which renal artery stenosis is the leading pathology. Up to 5 percent of all occurrences of hypertension are caused by renal artery stenosis, equating to as many as 3.5 to 4 million occurrences in the United States. Detecting renal artery stenosis is particularly important for ensuring that this potentially curable form of hypertension is identified and treated properly. Duplex Doppler ultrasonography is a good screening test in many patients, but it has limitations in larger persons and can overlook small accessory arteries. For patients with normal renal function but a high clinical index of suspicion for renovascular disease, contrast-enhanced magnetic resonance angiography and computed tomographic angiography are the most accurate imaging tests. For patients with diminished renal function, gadolinium-enhanced contrast magnetic resonance angiography is the best imaging test. However, caution is warranted because exposure to gadolinium contrast agents is associated with nephrogenic systemic fibrosis in patients with renal failure. The American College of Radiology has developed appropriateness criteria for imaging tests related to the diagnosis of renal artery stenosis. This article is a summary of the recommendations, with the advantages and limitations of each test.