This study will be conducted to evaluate the effect of once daily treatment with fluticasone furoate (FF) on lower leg growth in pediatric subjects with persistent asthma by using knemometry. Approximately 65 paediatric asthmatic subjects, aged 5 to 11 years (inclusive), will be screened to achieve 60 randomised and 50 evaluable subjects. Subjects meeting the eligibility criteria will enter the 2 week run-in period. After completing run-in period, each subject will be randomly allocated to one of two treatment sequences: inhaled fluticasone furoate followed by placebo or placebo followed by inhaled fluticasone furoate. Each treatment will be administered via the ELLIPTA™ dry powder inhaler. The two treatment periods will be separated by a two-week wash-out period. Subjects completing two treatment period will enter into 7 days follow-up period. ARNUITY™ ELLIPTA (FF) is approved in the US for adults and adolescents aged 12 and above.