The aim of the study was to evaluate the efficacy over 1 year of of felodipine ER 5 and 10 mg once daily (od) in 12 Caucasian patients with left ventricular hypertrophy secondary to primary hypertension. After a placebo period of 20 days, a physical examination and an echocardiography were performed in each patient. All patients started treatment with felodipine ER 5 mg. In 3 of the 12 patients the dose was increased to 10 mg od to control blood pressure (BP). BP was recorded every 2 weeks during the first 3 months, and at monthly intervals from the 3rd to the 12th months. An echocardiogram was taken at the end of the 3rd, 6th, 9th and 12th months. At the end of the placebo period, the mean SBP/DBP (+/-SD) was 178 +/- 11/104 +/- 5 mmHg. Mean SBP and DBP decreased significantly (p < 0.001) during the first 2 months to 138 +/- 10/86 +/- 3 mmHg and remained at this level until the end of the study. Mean left ventricular mass index (LVMI) decreased from 170 +/- 33 g/m2 after the placebo period to 115 +/- 19 g/m2 after 1 year (p < 0.01). It is concluded that felodipine ER 5 and 10 mg od over 1 year statistically significantly reduced both BP and LVMI.