The calcium channel blocker nifedipine is widely used in children with systemic hypertension: however, because of the short duration of action, three to four daily doses of the standard preparation are required. Amlodipine once-daily, a calcium channel blocker structurally related to nifedipine with an excellent bioavailability and a long elimination half-time, has been shown to reduce blood pressure in adults. No information is available on the use of amlodipine in childhood. The effects of amlodipine once-daily (5 to 10 mg) were therefore assessed in 28 paediatric patients with hypertension. Amlodipine was withdrawn in five patients who experienced oedema and flushing. In the remaining 23 patients blood pressure was significantly reduced 3 weeks after amlodipine (on average by 7/5 mm Hg) and further decreased at 12 weeks (by 21/12 mm Hg). Heart rate and body weight were unchanged. In eight patients concomitantly treated with cyclosporine, the blood level of this agent was stable throughout the study, thus not requiring any dose adjustment. CONCLUSION: The study illustrates the antihypertensive properties of amlodipine once-daily in paediatric hypertension. Amlodipine appears particularly indicated in patients concomitantly treated with cyclosporine.