There are a number of useful direct airway sampling procedures to help diagnose and monitor asthma in patients. However, non-invasive techniques are the ideal, especially in children, given the necessity of safe and repeatable measurements to monitor treatment efficacy and disease progression. Bronchoalveolar lavage (BAL) may be too invasive for clinical use in children, while questions still surround the utility of induced sputum (IS). More novel techniques, such as fractional exhaled nitric oxide (FE(NO)) and exhaled breath condensate (EBC), are still unproven. Eosinophilic airway inflammation is a major feature of childhood asthma, and it has been revealed as a major treatment target with inhaled corticosteroids. Moreover, treatment protocols governed by sputum eosinophil counts may be more efficacious - by reducing the frequency and severity of exacerbations - than treatment based on clinical symptoms and other traditional objective measures of lung function. The selection of an appropriate airway inflammation monitoring technique must take everything into consideration, including safety, reproducibility, repeatability, sensitivity to treatment, and the overall clinical/research goals.