Current guidelines on the management of childhood asthma have emphasised the important preventive role of inhaled corticosteroids, which should be used at the lowest possible doses that are compatible with good disease control. However, some children do not respond to inhaled corticosteroids, the most common reasons for which are inability to use conventional hand-held inhalers (plus spacers and face masks) effectively or lack of cooperation with them, particularly among infants and young children. In these patients, nebulisers have proved effective in administering corticosteroids, and this form of delivery is often preferred by both the children and their parents, despite their longer administration times (commonly around 10 minutes). Compliance with these devices may therefore be better than with a conventional pressurised metered-dose inhaler plus spacer and face mask. Recent studies with nebulised budesonide have demonstrated that once-daily administration is as effective in maintaining control of asthma symptoms in children as the usual twice-daily administration. In children with moderately severe persistent asthma, the improvement provided by once-daily nebulised doses of 1.0 mg budesonide has been found to be equivalent to that with twice-daily doses of 0.25 or 0.5 mg, indicating that once-daily therapy is an effective option that can be considered in many patients. In view of the time-consuming nature of nebuliser administration, reduction of the frequency of corticosteroid administration from twice to once daily may be useful in simplifying the treatment programme and improving compliance with it. This may be beneficial in reducing under-utilisation of inhaled corticosteroids in children with asthma and improving long term control of the disease.