and they can be particularly useful in longitudinal studies when repeated measurements are important (3, 4). The value of endobronchial biopsy analysis remains crucial, however, because it is the only way to appreciate inflammation and remodeling of the bronchi on the same sample. Recent studies have investigated whether therapeutic interventions, including inhaled corticosteroids (ICSs), can interfere with inflammation and structural changes in situ. Endobronchial biopsy has been promoted as a valuable tool in this research, as its intersubject reproducibility is satisfactory, provided that a sufficient number of patients are studied. In this article, we survey the current knowledge about the ability of ICS treatment to affect the pathology of asthma and COPD, based on the results of endobronchial biopsy analysis.