Left ventricular hypertrophy (LVH) is a common complication of essential hypertension and an independent risk factor for the development of cardiovascular disease. Therefore, antihypertensive treatment should decrease blood pressure (BP) and reverse LVH. However, antihypertensive drugs have been shown to have different effects on LVH despite similar effects on BP reduction. Although lowering BP produces a beneficial effect on LVH per se, meta-analyses of clinical trials have indicated that angiotensin-converting enzyme (ACE) inhibitors decrease left ventricular mass (LVM) to a greater extent than do some other antihypertensives. The aim of this study was to evaluate the effect of a 24-week treatment with the ACE inhibitor moexipril (15 mg once daily) on the regression of LVH in hypertensive patients. This was a multicenter, international, single-blind, single-group, nonrandomized study. After a wash-out placebo period of 2 weeks, 15 mg moexipril once daily was administered for 24 weeks followed by a 2-week follow-up placebo period. Subjects with mild to moderate essential hypertension were screened; those with LVH [defined as an LVM indexed for body surface area (LVMIs) >111 g/m in men and LVMIs >106 g/m in women] were eligible to participate in this study. Echocardiograms were recorded on videotape and sent to a centralized laboratory for reading by 2 independent experts blinded for treatment, center, and visit; the mean values of these readings were calculated and used for analysis. Valid echocardiographic data were obtained from 72 patients (50 males, 22 females) with a mean age of 49 +/- 11 years. Analysis showed significant decrease of LVMIs (121 +/- 20 versus 103 +/- 17 g/m; P < 0.001) and BP (152 +/- 12/96 +/- 9 versus 140 +/- 13/86 +/- 9 mm Hg; P < 0.001) with moexipril. For patients who met LVMI inclusion criteria after centralized, blinded readings, the decrease from baseline in LVMIs was 23.4 g/m. The decrease in LVMIs was independent from the regression to the mean phenomenon as observed from the follow-up placebo period. Moexipril 15 mg once daily administered for 24 weeks resulted in a significant reversal of LVH in patients with essential hypertension. The result compares favorably with results previously obtained in trials of similar duration with other ACE inhibitors.