To examine the long-term efficacy and safety of amlodipine in hypertensive children, data on prolonged use (> or = 6 months) of amlodipine in 33 children were reviewed. All children received amlodipine as sole therapy for their hypertension. Causes of hypertension included solid organ transplant (n=19), renal disease (n=7) primary hypertension (n=6), and drug-induced hypertension (n=1). Mean patient age at the start of amlodipine treatment was 9.8+/-4.8 years (range 1.3-16.9); there were 19 boys and 14 girls. Mean duration of amlodipine treatment was 20.4+/-11.5 months (range 6-48). Analysis of blood pressure and dosing data revealed that blood pressure reduction was sustained throughout the period of amlodipine treatment, while amlodipine dose remained stable (mean effective daily dose 0.17+/-0.12 mg/kg). No patient required discontinuation of amlodipine because of adverse effects. This small study suggests that prolonged amlodipine treatment is well tolerated in hypertensive children and provides sustained blood pressure control. Further studies are necessary to determine what effects if any long-term calcium channel blocker treatment has on the growth and development of children with hypertension.