Conflict of interest: none declared. Financial support: none declared.

• There is controversy about the effectiveness of monitoring of asthma treatment based on the fraction of exhaled nitric oxide (FeNO).

• We performed a systematic review of the literature on the effectiveness of FeNO-guided asthma treatment in children.

• Up to the end of March 2009, four randomised controlled trials were published, but the results of the trials could not be pooled. Their methodological quality was moderate to high.

• There was no significant effect of FeNO-guided asthma treatment on the number of symptom-free days, asthma exacerbations, hospital admissions, pulmonary function history (except one trial) and quality of life.

• There was a moderate effect on prednisone use. Children receiving FeNO-guided treatment used prednisone less often than children whose treatment was based on symptoms. However, children receiving FeNO-guided treatment used higher doses of inhaled corticosteroids.

• At this moment, FeNO-guided asthma treatment cannot be recommended in general practice and paediatric care.