Asthma is a chronic inflammatory disease of the airways. Guidelines for the management of asthma use a stepwise approach to pharmacotherapy based on assessment of asthma severity and lung function. However, the assessment of asthma control presently relies on the frequency of symptoms or the frequency of use of short-acting β2-adrenergic agonists. There is no simple, non-invasive technique for the assessment of airway inflammation in asthma before. Exhaled nitric oxide (ENO) used as an aid to the evaluation of childhood asthma is receiving attention from clinicians alike because it offers a noninvasive means to directly monitor airway inflammation. Exhaled NO levels significantly increase in individuals with childhood asthma before symptoms emerging and decrease with corticosteroid administration. Exhaled NO levels correlates with the number of eosinophils in induced sputum. These observations support an association between ENO levels and airway inflammation. This review presents the update on current opportunities regarding the use of ENO in its potential usage for childhood asthma diagnosis and treatment, including changes in disease severity, symptom response, and technical measurement issues. However, the large population and long-term longitudinal studies are necessary to fully evaluate the clinical utility of EeNO in childhood asthma management. (J Pediatr Resp Dis 2011; 7:93-97)