Effective treatment of systolic hypertension in elderly patients remains a major therapeutic challenge. A multicenter, double-blind, randomized controlled trial with sacubitril/valsartan (LCZ696), a first-in-class angiotensin receptor neprilysin inhibitor, was conducted to determine its effects versus olmesartan (angiotensin receptor blocker) on central aortic pressures, in elderly patients (aged ≥60 years) with systolic hypertension and pulse pressure >60 mm Hg, indicative of arterial stiffness. Patients (n=454; mean age, 67.7 years; mean seated systolic blood pressure, 158.6 mm Hg; mean seated pulse pressure, 69.7 mm Hg) were randomized to receive once-daily sacubitril/valsartan 200 mg or olmesartan 20 mg, force titrated to double the initial doses after 4 weeks, before primary assessment at 12 weeks. The study extended double-blind treatment for 12 to 52 weeks, during which amlodipine (2.5–5 mg) and subsequently hydrochlorothiazide (6.25–25 mg) were added-on for patients not achieving blood pressure target (<140/90). At week 12, sacubitril/valsartan reduced central aortic systolic pressure (primary assessment) greater than olmesartan by −3.7 mm Hg (P=0.010), further corroborated by secondary assessments at week 12 (central aortic pulse pressure, −2.4 mm Hg, P<0.012; mean 24-hour ambulatory brachial systolic blood pressure and central aortic systolic pressure, −4.1 mm Hg and −3.6 mm Hg, respectively, both P<0.001). Differences in 24-hour ambulatory pressures were pronounced during sleep. After 52 weeks, blood pressure parameters were similar between treatments (P<0.002); however, more patients required add-on antihypertensive therapy with olmesartan (47%) versus sacubitril/valsartan (32%; P<0.002). Both treatments were equally well tolerated. The PARAMETER study (Prospective Comparison of Angiotensin Receptor Neprilysin Inhibitor With Angiotensin Receptor Blocker Measuring Arterial Stiffness in the Elderly), for the first time, demonstrated superiority of sacubitril/valsartan versus olmesartan in reducing clinic and ambulatory central aortic and brachial pressures in elderly patients with systolic hypertension and stiff arteries.