The effect of 6 months of treatment with indapamide (IND, 2.5 mg/day) on regression of left ventricular hypertrophy (LVH), an independent predictor of poor prognosis in hypertension, was compared by echocardiography to that of nifedipine (NFD, 40 mg/day), enalapril (ENL, 20 mg/day), atenolol (ATL, 100 mg/day), and hydrochlorothiazide (HCTZ, 25 mg/day) in four parallel double-blind studies in 151 hypertensive patients with a diastolic blood pressure between 95 and 120 mm Hg and a raised left ventricular mass index (LVMI) (mg/m2) (Devereux). Patients were randomized to IND or comparator following a 2-week washout (1 month in the IND vs. ATL study). Respective baseline and 6-month LVMI values (mg/m2) were: IND (n = 20) vs. HCTZ (n = 20): 151.4 +/- 6.3 and 125.70 +/- 4.6 (p0.001) vs. 141.3 +/- 6.6 and 135.6 +/- 8.3 (p = N.S.); IND (n = 22) vs NFD (n = 19): 144.1 +/- 5.3 and 125.1 +/- 4.3 (p0.001) vs. 170.4 +/- 6.6 and 148.2 +/- 6.2 (p0.001); IND (n = 9) vs. ENL (n = 9): 155.1 +/- 6.3 and 143.4 +/- 5.2 (p0.001) vs. 142.0 +/- 6.7 and 130.0 +/- 5.9 (p0.001); IND (n = 17) vs. ATL (n = 12): 146.2 +/- 5.1 and 130.8 +/- 6.5 (p0.001) vs. 156.7 +/- 8.4 and 142.9 +/- 10.3 (p0.01). All drugs significantly reduced diastolic blood pressure, and all except HCTZ induced a significant and similar reduction in left ventricular mass.