The effect of the inhaled topical steroid budesonide on adrenal function was evaluated in 33 children (aged 7-15 years) with moderate bronchial asthma. The trial was designed as a prospective single-blind study of the effect of budesonide in daily doses of 200 microgram through 400 microgram to 800 micrograms in three randomized consecutive periods of 8 weeks. The unstimulated diurnal production of cortisol was assessed by measurement of free cortisol in 24-hour urine samples at the end of each period. No significant dose-related suppression was found. The cortisol production did not differ significantly during treatment with 800 microgram budesonide as compared to treatment with 200 microgram budesonide (95% confidence interval: 74%-112%). It is concluded, that budesonide is a topical steroid with a favourable ratio between topical and systemic effects in asthmatic children.