BACKGROUND Experimental and clinical evidence suggests that calcium-channel blockers may retard the atherosclerotic process after long-term treatment. Whether these effects exist after intermediate-term treatment in hypertensive patients is mainly unknown. OBJECTIVE To determine the 26-week effects of the long-acting calcium-channel blocker nifedipine on intima media thickness (IMT) in newly found hypertensive patients. METHODS Open-label study with blinded end-point analysis. METHODS From a population survey, 131 previously untreated mild hypertensives (4 x systolic blood pressure between 160 and 220 mmHg and/or diastolic blood pressure between 95 and 115 mmHg) were included. Patients were treated with long-acting nifedipine 30-60 mg targeted to reach a predetermined drop in blood pressure. Prior to and after 26 weeks of treatment, IMT was measured by ultrasonography in the carotid and femoral artery. The combined mean maximal far wall IMT was used as primary endpoint. Change from baseline was evaluated by paired t-test in an intention-to-treat analysis. RESULTS The mean maximal far wall IMT at baseline was 1.03 +/- 0.23 mm, and decreased by 0.078 mm (95% confidence interval, CI 0.044-0.111) after treatment. Regression analysis, including baseline IMT and changes of blood pressure, showed that reduction of IMT was mostly influenced by baseline IMT (p < 0.001; model R2 = 0.1). CONCLUSIONS Our observations show that 26 weeks of nifedipine treatment inhibits IMT progression in these newly found hypertensive patients. This effect was mostly seen in arterial walls with highest IMT before treatment, suggesting that patients with highest cardiovascular risk benefit most of antihypertensive treatment.