BACKGROUND: Prior unblinded studies have suggested that catheter-based renal-artery denervation reduces blood pressure in patients with resistant hypertension. METHODS: We designed a prospective, single-blind, randomized, sham-controlled trial. Patients with severe resistant hypertension were randomly assigned in a 2:1 ratio to undergo renal denervation or a sham procedure. Before randomization, patients were receiving a stable antihypertensive regimen involving maximally tolerated doses of at least three drugs, including a diuretic. The primary efficacy end point was the change in office systolic blood pressure at 6 months; a secondary efficacy end point was the change in mean 24-hour ambulatory systolic blood pressure. The primary safety end point was a composite of death, end-stage renal disease, embolic events resulting in end-organ damage, renovascular complications, or hypertensive crisis at 1 month or new renal-artery stenosis of more than 70% at 6 months. RESULTS: A total of 535 patients underwent randomization. The mean (±SD) change in systolic blood pressure at 6 months was -14.13±23.93 mm Hg in the denervation group as compared with -11.74±25.94 mm Hg in the sham-procedure group (P<0.001 for both comparisons of the change from baseline), for a difference of -2.39 mm Hg (95% confidence interval [CI], -6.89 to 2.12; P = 0.26 for superiority with a margin of 5 mm Hg). The change in 24-hour ambulatory systolic blood pressure was -6.75±15.11 mm Hg in the denervation group and -4.79±17.25 mm Hg in the sham-procedure group, for a difference of -1.96 mm Hg (95% CI, -4.97 to 1.06; P = 0.98 for superiority with a margin of 2 mm Hg). There were no significant differences in safety between the two groups. CONCLUSIONS: This blinded trial did not show a significant reduction of systolic blood pressure in patients with resistant hypertension 6 months after renal-artery denervation as compared with a sham control. Copyright © 2014 Massachusetts Medical Society.