Renal artery stenosis not only causes severe hypertension, but if left untreated, can progress to renal failure. A 64-year-old woman with a serum creatinine of 1.8 mg/dL and mild proteinuria developed progressively severe hypertension that was resistant to a calcium channel blocker. The patient received lisinopril, which was discontinued after 2 days because of nonspecific symptoms. One week later, an intravenous pyelogram showed a normal-sized but poorly functioning left kidney and a nonfunctional right kidney. The serum creatinine increased to 11.7 mg/dL and the patient was begun on hemodialysis. A renal arteriogram performed 6 weeks later for persistent hypertension showed bilateral renal artery occlusion; renal vein renin values from the left kidney were higher than those from the right kidney. After 11 weeks of hemodialysis, thrombolytic therapy followed by angioplasty was performed. Three weeks later, the renal function had returned to baseline (serum creatinine of 1.8 mg/dL) and hypertension was controlled with a beta-blocker. Renal artery stenosis is a potentially reversible cause of renal failure and should be considered in the evaluation of elderly patients with hypertension, even in the presence of renal failure.