Although better insights into the natural course of cystic fibrosis (CF) have led to treatment approaches that have improved pulmonary health and increased the life expectancy of individuals with this disorder, lung disease remains the main cause of morbidity and mortality in patients with CF. Evidence suggests that airway epithelial defects in ions-water transport lead to dehydrated mucus, impaired mucus clearance, and mucus adhesion to airway surfaces. An increase in mucin secretion is also suggested by the formation of endobronchial mucus plaques and plugs, which become the main sites of air flow obstruction, infection, and inflammation conducing to early small airways disease followed by the development of bronchiectasis. The lung involvement is usually progressive with intermittent exacerbations. Aggressive management and advances in treatment delay, but, do not prevent progression of lung disease. Respiratory failure ensues and is the major cause of death. The lung parenchyma is virtually untouched for much of the course of the disease. This review focuses on the lung involvement in cystic fibrosis and summarizes new developments on the diagnostic approach of CF and pathogenesis of related lung disease. Current therapeutic modalities, novel therapies targeting the basic genetic defect, and lung transplantation are also reviewed.