Cystic fibrosis is a common genetic disorder caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Although the link between the mutations of the CFTR gene and the progressive lung disease is not completely understood, noteworthy advances have been made in the understanding of the mechanisms underlying lung injury in CF. The pathophysiologic cascade starts with CFTR dysfunction resulting from mutations of the CFTR gene, and leading to abnormal ion and water transport across airway epithelia. Abnormal airway surface liquid may in turn lead to impairment of mucociliary clearance, airway mucosal anti-microbial defenses, chronic bacterial infection and inflammation. Each of these steps has been elucidated in more detail in the recent years. This is of relevance from a therapeutic viewpoint. New therapeutic interventions include gene therapy, agents that may circumvent the defect in intracellular processing of mutated CFTR, agents that may modulate defects in epithelial ion transport, and anti-inflammatory agents.