Background - A significant number (20% to 40%) of hypertensive patients with renal artery stenosis will not have blood pressure improvement after successful percutaneous revascularization. Identifying a group of patients with refractory hypertension and renal artery stenosis who are likely to respond to renal stent placement would be beneficial. Methods and Results - Brain natriuretic peptide (BNP) was measured in 27 patients with refractory hypertension and significant renal artery stenosis before and after successful renal artery stent placement. This neuropeptide was elevated ( median, 187 pg/mL; 25th to 75th percentiles, 89 to 306 pg/mL) before stent placement and fell within 24 hours of the successful stent procedure ( 96 pg/mL; 25th to 75th percentiles, 61 to 182 pg/mL; P = 0.002), remaining low ( 85 pg/mL; 25th to 75th percentiles, 43 to 171 pg/mL) at follow-up. Clinical improvement in hypertension was observed in the patients with a baseline BNP > 80 pg/mL ( n = 22) in 17 patients (77%) compared with 0% of the patients with a baseline BNP > 80 pg/mL ( n = 5) ( P = 0.001). After correction for glomerular filtration rate, BNP was strongly correlated with improvement in hypertension. Conclusions - BNP is increased in patients with severe renal artery stenosis and decreases after successful stent revascularization. In addition, an elevated baseline BNP level of > 80 pg/mL appears to be a good predictor of a blood pressure response after successful stent revascularization.