Reversal of left ventricular (LV) hypertrophy is an important goal of antihypertensive therapy. This phase 3b study compared the ability of the angiotensin receptor blocker olmesartan medoxomil with the calcium channel blocker amlodipine besylate to induce regression of LV hypertrophy and vascular hypertrophy after achieving blood pressure (BP) goal. After a washout phase, 102 patients with hypertension and LV hypertrophy were randomized to olmesartan medoxomil 20 mg/day, up titrated to 40 mg/day, or amlodipine 5 mg/day, up titrated to 10 mg/day, for up to 4 weeks until a BP goal of <140/90 mm Hg (<130/85 mm Hg for diabetes) was achieved (hydrochlorothiazide 25 mg/day and terazosin 1 to 5 mg/day 2 times/day could be added if needed). Upon achieving the BP goal or by week 8, and again at weeks 26 and 52, assessments of LV mass and compliance and arterial structure and function were performed by echocardiography, Doppler flow, and arterial ultrasonography, respectively. There was no statistically significant percent change in LV mass at 52 weeks in either treatment group (11.6% with olmesartan medoxomil vs 2.9% with amlodipine) and no statistically significant difference between treatment groups. There were no significant changes in LV compliance or carotid or femoral artery wall-to-lumen ratios in either treatment group at 52 weeks. In conclusion, there did not appear to be a clinically significant BP-independent effect with olmesartan medoxomil or amlodipine on LV mass decrease, diastolic function or vascular structure, and compliance in patients with hypertension and LV hypertrophy.