Inhaled steroids are the most effective long-term treatment of persistent asthma but many children are unable to use correctly the available inhalers. Administration of nebulized corticosteroids has some advantages over the administration with pressurised metered-dose inhalers (pMDls). The objective of this multicenter randomised study was to compare the efficacy and tolerability of nebulized corticosteroids in paediatric patients with asthma. 127 patients aged > or = 6 and < or = 14 years with a diagnosis of mild to moderate persistent asthma (PEFR % predicted > 50% and < 85%) and positive response to the reversibility test were randomized. The patients were assigned by randomisation to one of the two treatment groups (4 weeks): beclomethasone dipropionate (BDP) 800 microg/daily b.i.d. (n = 66) or budesonide (BUD) 1000 microg/daily b.i.d. (n = 61) both administered by nebulizer. The primary efficacy end point was the final mean of PEFR measured at clinical visit (clinic PEFR). In the BDP group clinic PEFR increased from 177.5 +/- 80 L/min to 246.6 +/- 84.2 L/min (p < 0.001 vs baseline), while in the BUD group the increase was from 180.4 +/- 77.8/min to 260.9 +/- 84.1 L/min (p < 0.001 vs baseline) (NS between treatments). FEV1 (% predicted) increased from 77.8% to 92.7% (p < 0.001 vs baseline) and from 74.1% to 95.9% (p < 0.001 vs baseline) in BDP and BUD group respectively (NS between treatments). Patients reduced the use of salbutamol rescue medication by 76% and 81% in BDP and BUD group respectively (p < 0.001 vs baseline, NS between treatments). 4 patients in the BDP group and 2 in the BUD group reported adverse events (AEs). AEs were mild to moderate and never there was the need to discontinue the treatments. In conclusion the results of this study demonstrate that both BDP (800 microg/daily) and BUD (1000 microg/daily) administered by nebulization are effective and with a acceptable safety and tolerability profile.