The airway epithelium is a complex physicochemical barrier to inhaled irritants, allergens, pathogens and noxious substances. It is now clear that bronchial epithelium, in addition to acting as a barrier, plays a crucial role in initiating and augmenting pulmonary tissue defence by contributing various epithelial repair mechanisms. The pulmonary repair process by the contribution of epithelial cell functional transition is tried to be explained by epithelial-mesenchymal transition hypothesis. It is widely accepted that the relation of the epithelium with other submucosal cells such as dendritic cells, smooth muscle cells and fibroblasts has a sentinal role in the initiation and development of various pulmonary diseases. The recent evidence shows that some different repair mechanisms or altered repair process might play role in pathogenesis of pulmonary diseases including acute respiratory distress syndrome, asthma, cystic fibrosis, chronic obstructive pulmonary disease, and idiopathic pulmonary fibrosis. The purpose of this review is to revise the literature about the role of tissue repair mechanisms in the pathogenesis of various pulmonary diseases.