The current study investigated the efficacy and safety of olmesartan medoxomil in children with hypertension, defined as systolic blood pressure measured at or above the 95th percentile (90th percentile for patients with diabetes, glomerular kidney disease, or family history of hypertension) for age, gender, and height while off any antihypertensive medication. The active treatment phase was conducted in 2 periods, with 2 cohorts in each period (cohort A, 62% white; cohort B, 100% Black). In period 1, patients stratified by weight received low-dose (2.5 or 5 mg) or high-dose (20 or 40 mg) olmesartan medoxomil daily for 3 weeks. In period 2, patients maintained their olmesartan medoxomil dose or initiated placebo washout for an additional 2 weeks. Period 1 efficacy results showed a dose-dependent, statistically significant reduction in seated trough systolic and diastolic blood pressure for both cohorts, with mean blood pressure reductions numerically smaller in cohort B than in cohort A. The olmesartan medoxomil dose response remained statistically significant when adjusted for body weight. In period 2, blood pressure control decreased in those patients switching to placebo, whereas patients continuing to receive olmesartan medoxomil therapy maintained consistent blood pressure reduction. Adverse events were generally mild and unrelated to study medication. Olmesartan medoxomil was safe and efficacious in children with hypertension, resulting in significant blood pressure reductions.