The importance of airway inflammation in the pathophysiology of bronchial asthma has been recognized recently. This inflammation is organized by the interaction between inflammatory cells and the cells which compose airway structures. We studied the role of airway epithelium in airway hyperresponsiveness and airway inflammation, which are the major characteristics of bronchial asthma, and demonstrated a close relationship between them. On the bases of these data and the data reported by many other researchers, and from the point of view of airway inflammation, we discussed the possible roles of airway epithelium in bronchial asthma.