: In cystic fibrosis, airway infection and inflammation lead to chronic progressive lung disease. The pathogenesis of cystic fibrosis is still not completely understood, but increasing evidence indicates that the disease process occurs in young patients. Treatment of respiratory symptoms in young patients, although not well studied, is commonly accepted and includes the full range of treatments used in older patients-secretion clearance techniques, bronchodilators, anti-inflammatory agents, and antibiotics by oral, inhaled, and systemic routes. It is not clear, however, whether early treatment can delay or prevent progressive lung disease in these patients. Outcome measures, including determination of infant lung function, imaging techniques, and direct lower airway sampling through bronchoalveolar lavage are under development and will allow large, multicenter interventional trials in young children. These studies will be aimed at delaying the initiation of lung disease and slowing disease progression.