In adults, asthma treatment with high doses of inhaled corticosteroids has resulted in dermal thinning. The aim of this study was to investigate the skin thickness in children with asthma during budesonide treatment. In a double-blind study, 113 children, 5-10 y old, with persistent asthma received budesonide 400 microg twice daily for 1 mo and thereafter 200 microg twice daily for 5 mo. Thereafter, 56 children received 100 microg twice daily for 1 y, whereas 57 other children used budesonide periodically for exacerbations. An additional 54 children were treated with disodium cromoglycate (DSCG) for 18 mo. Skin thickness was measured on each forearm before and after treatment for 6, 12, and 18 mo using a 20-MHz high-resolution ultrasonic device. The initial 6-mo budesonide treatment resulted in a greater reduction in mean skin thickness in the forearms compared with DSCG (right: -35.9 versus -5.9 microm; p = 0.004; left: -30.6 versus -7.3 microm; p = 0.03). At month 18, the inter-group differences were no longer significant. Budesonide inhalations in daily doses of 400-800 microg in prepubertal children with newly detected asthma may cause minor dermal thinning. The changes were reversible during low dose or periodic treatment with budesonide.