Aim: The aim of the present study was to evaluate (1) the prevalence and patterns of left ventricular hypertrophy (LVH) and (2) the impact of blood pressure (BP) control, assessed by clinical and 24-hour ambulatory BP monitoring (ABPM) criteria on the persistence of LVH in a representative sample of treated patients attending our Hypertension Clinic. Methods: One hundred consecutive essential hypertensives (61 m/39 f, age 56± 9 years) regularly followed up by the same medical team (average period 52 months, 12–156 months) were included in the study and underwent 24-hour ABPM and complete echocardiographic examination. Results: Twenty-eight of the 100 patients were found to have LVH [left ventricular mass index (LVMI) >125 g/m<sup>2</sup> in men and >110 g/m<sup>2</sup> in women]; LVH was eccentric in 20 patients and concentric in the remaining 8. LVMI did not correlate with clinical BP values but only with ABPM values (mean 24 h systolic r = 0.34, p <0.01; diastolic r = 0.37, p <0.01). The prevalence of LVH in patients controlled according to clinical BP criteria (n = 43, BP <140/90 mm Hg) was 19%, in patients controlled according to ABPM criteria (n = 30, BP during daytime <132/85 mm Hg) 17%, and in those controlled with both criteria (n = 16) 6% (p <0.01). Conclusions: The results of this study suggest that the eccentric type of LVH is the prevalent pattern in chronically treated patients. The persistence of LVH is significantly dependent on BP levels achieved during treatment; indeed the prevalence of LVH is very low in patients with an optimal BP control, whereas it is elevated (37%) in uncontrolled patients.