Nebulization for the administration of high doses of inhaled corticosteroids can benefit steroid-dependent asthmatics. The objective of this double-blind, double-dummy, multicentre, randomized, parallel-group study was to compare the efficacy and safety of high-dose corticosteroids given by nebulization or metered-dose inhalation in adult patients with asthma. Following a 2-week run-in period, 124 patients, aged 18-70 years, with moderate to severe asthma treated with high-dose inhaled steroids were randomized to one of two treatment groups for 12 weeks: beclometasone dipropionate (BDP) suspension for nebulization 3,000-4,000 microgday(-1) b.i.d. given via a nebulizer (n = 63), or BDP spray 1,500-2000 microgday(-1) b.i.d. given via a metered-dose inhaler (MDI) plus spacer (BDP MDI) (n = 61). Comparable improvements over baseline, which were statistically significant in most cases, were reported at study end for the two treatment groups in the various efficacy parameters evaluated (pulmonary function tests, clinical symptoms scores, and the use of rescue salbutamol). The primary efficacy endpoint was morning pulmonary expiratory flow rate (PEFR). For the intent-to-treat population, in the BDP nebulization group mean morning PEFR increased statistically significantly from 308.7 +/- 107.81 min(-1) to 3 19.2 +/- 104.01 min(-1) while in the BDP MDI group the increase was from 301.5 +/- 94.71 min(-1) to 309.3 +/- 86.71 min(-1). The two treatments were equally well tolerated.A total of 19 patients in each group reported adverse events during the treatment period, and these were generally mild-moderate in severity. In conclusion, the results of this study demonstrate that BDP suspension for nebulization 3,000-4,000 microg day(-1) given via a nebulizer and BDP spray 1,500-2,000 microg day(-1) given via an MDI plus spacer are equally effective, with an acceptable safety and tolerability profile, when used in steroid-dependent adult patients with moderate to severe asthma.