There have been no previous large, well-designed direct comparisons of the effects of fluticasone propionate (FP) and budesonide (BUD) on growth in children. This randomised, double-blind study compared the effects on growth of FP and BUD in children aged 6-9 years with persistent asthma. Following a 6-month run-in period (without inhaled corticosteroids), patients with normal growth velocity were randomised to 12 months' treatment with FP 100 micro g bd (n=114) or BUD 200 micro g bd (n=119). Growth velocity was determined by stadiometric height measurement. Lung function, asthma symptoms and use of relief medication were also assessed. Annualised mean growth velocity during run-in was comparable in the two groups (FP: 5.9 cm/yr; BUD: 6.0 cm/yr). During the treatment period, adjusted mean growth velocity was significantly higher in the FP than the BUD group (5.5 cm/yr vs 4.6 cm/yr; P<0.001). Asthma control improved similarly in both treatment groups. Bone mineral density and overnight urinary cortisol:creatinine ratios were similar in the two groups. Drug-related adverse events were reported among 3% of FP-treated children, compared with 2% for BUD. In conclusion, this study demonstrates that FP for childhood asthma has significantly less impact on childhood growth velocity than a therapeutically equivalent dose of BUD.