Inhaled corticosteroids (ICS) are preferred drugs for the long-term treatment of all severities of asthma in children. However, data about the safety of ICS in infants is lacking. So, it is essential to do further clinical studies to examine the safety and efficacy of ICS in this population. In this study, the effects of nebulized budesonide and nebulized fluticasone propionate suspensions on hypothalamic–pituitary–adrenal axis is examined in infants with recurrent or persistent wheeze. Thirty-one children aged 6–24 months admitted to our hospital between January and December 2005 with symptoms of recurrent or persistent wheeze were included in the study. The patients were randomly allocated to receive 0.25 mg BUD or 0.25 mg fluticasone propionate twice daily for 6 wk and half dose for another 6 wk with a jet nebulizer at home. Blood samples for basal cortisol concentration, adrenocarticotropic hormone, glucose, HbA1c and electrolytes were obtained at the beginning and at the end of the study. Adrenal function assessment was based on changes in cosyntropin-stimulated plasma cortisol levels. The study was completed with 31 patients, 16 of whom received BUD and 15 FP. All patients except one had plasma cortisol concentrations above 500 nmol/l (18 μg/dl) or had an incremental rise in cortisol of >200 nmol/l after stimulation. Although nebulized steroids seem to be safe in infancy, we recommend that adrenal functions should be tested periodically during long-term treatment with nebulized steroids.