Background The aim of this study was to assess potential differences in the 24-h antihypertensive response to treatment with the controlled-onset, extended-release (COER) calcium antagonist, verapamil in men versus women and older versus younger patients with hypertension. Methods: Meta-analyses were performed of three prospective randomized, double-blind, placebo-controlled trials with COER-verapamil in patients with mid–stage I to stage III essential hypertension. The trials were conducted at medical clinics in the US and Canada in patients with a mean office diastolic blood pressure (BP) of 95 to 115 mm Hg on 2 consecutive weeks and a mean daytime diastolic BP >90 mm Hg. Patients were randomized to treatment with 180 to 540 mg/day of COER-verapamil ( N = 273) or placebo ( N = 125). Changes from baseline in ambulatory BP and heart rate after COER-verapamil were compared in men versus women and in older versus younger patients. Results: Treatment with COER-verapamil caused significant reductions in 24-h and early-morning systolic and diastolic BP in all of the subpopulations as compared with placebo ( P < .001). COER-verapamil induced a greater reduction in both 24-h systolic (−15.1 v −10.0 mm Hg; P < .001) and diastolic (−10.4 v −8.2 mm Hg; P = .003) BP in women compared with men. Older patients showed a greater mean reduction in 24-h diastolic BP (−10.2 v −8.2 mm Hg; P < .05) and heart rate (−5.7 v −4.4 beats/min; P < .05) compared with younger patients. Side effects were similar in all of the COER-verapamil treatment groups. Conclusions Both gender and age were significant determinants of the response to COER-verapamil. The antihypertensive effect of verapamil is greater in women than in men and in older patients compared with younger patients.