77 children, aged 11 to 36 months (mean 24) with moderately severe recurrent wheezing, were treated with budesonide pressurised aerosol 400 micrograms twice daily or placebo for 12 weeks in a double-blind, parallel-group trial. Aerosols were inhaled from a spacer with a facemask. Budesonide significantly improved symptom scores of wheezing, sleep disturbance, and patient happiness. The frequency of severe exacerbations that required a course of oral prednisolone was also significantly reduced. The treatment effect appeared to be fully established after 6-8 weeks and no side-effects could be ascribed to the active treatment. The findings indicate that young children below 3 years of age can inhale a pressurised aerosol from a spacer with a facemask. Use of topically active glucocorticosteroids with this simple device may reduce symptoms and distress in young children with moderately severe recurrent wheeze and dyspnoea, and possibly reduce their requirement for oral steroids.