Abnormal lung function and high exhaled nitric oxide (FeNO) have been reported in asymptomatic patients with asthma. The investigators aimed to assess whether FeNO and FEF25-75 improve concurrently after treatment with inhaled corticosteroid (ICS) in patients with controlled asthma. Geometric mean (GM) FeNO and spirometric values in patients 8 to 16 years of age who maintained asthma control without controller medication were compared with healthy controls and patients with uncontrolled asthma who were also not receiving controller medications. Patients with controlled asthma and high FeNO (> 25 ppb) were randomized to ICS treatment or to remain untreated. Changes in spirometric values and GM FeNO from baseline were evaluated after 6 weeks.