['In cross-sectional studies, ambulatory blood pressure (ABP) correlates more closely than clinic BP with the organ damage of hypertension. Whether ABP predicts development or regression of organ damage over time better than clinic BP, however, is unknown.', 'In 206 essential hypertensive subjects with left ventricular hypertrophy (LVH), we measured clinic supine BP, 24-hour ABP, and left ventricular mass index (LVMI, echocardiography) before and after 12 months of treatment with lisinopril (20 mg UID) without or with hydrochlorothiazide (12.5 or 25 mg UID). Measurements included random-zero, clinic orthostatic, and home BP. In all, 184 subjects completed the 12-month treatment period. Before treatment, clinic supine BP was 165 +/- 15/105 +/- 5 mm Hg (systolic/diastolic), 24-hour average BP was 149 +/- 16/95 +/- 11 mm Hg, and LVMI was 158 +/- 32 g/m2. At the end of treatment, they were 139 +/- 12/87 +/- 7 mm Hg, 131 +/- 12/83 +/- 10 mm Hg, and 133 +/- 26 g/m2, respectively (P < .01 for all). Before treatment, LVMI did not correlate with clinic BP, but it showed a correlation with systolic and diastolic 24-hour average BP (r = .34/.27, P < .01). The LVMI reduction was not related to the reduction in clinic BP, but it was related to the reduction in 24-hour average BP (r = .42/.38, P < .01). Treatment-induced changes in average daytime and nighttime BPs correlated with LVMI changes as strongly as 24-hour BP changes. No substantial advantage over clinic supine BP was shown by clinic orthostatic, random-zero, and home BP.'] Is ambulatory blood pressure superior to clinic blood pressure in predicting treatment-induced regression of left ventricular hypertrophy . SAMPLE Study Group . Study on Ambulatory Monitoring of Blood Pressure and Lisinopril Evaluation?