Bronchiectasis is defined in current medical parlance as the abnormal and permanent dilatation of one or more bronchi, and in clinical practice, the condition is often characterized by features of chronic bronchial infection. Apart from occurring as a primary lung disease, bronchiectasis is a major component of two other disease entities, cystic fibrosis and diffuse panbronchiolitis. Although the three conditions have distinctly different underlying causes, they share the similarity of a predominantly neutrophilic airways inflammation, and the persistent bronchial infection by bacteria, in particular Pseudomonas aeruginosa. Hence, new knowledge in one disease may be explored and applied in the others.