ObjectivesTo determine the prevalence of bronchiectasis in young children with cystic fibrosis (CF) diagnosed after newborn screening (NBS) and the relationship of bronchiectasis to pulmonary inflammation and infection.Study designChildren were diagnosed with CF after NBS. Computed tomography and bronchoalveolar lavage were performed with anesthesia (n = 96). Scans were analyzed for the presence and extent of abnormalities.ResultsThe prevalence of bronchiectasis was 22% and increased with age (P = .001). Factors associated with bronchiectasis included absolute neutrophil count (P = .03), neutrophil elastase concentration (P = .001), and Pseudomonas aeruginosa infection (P = .03).ConclusionsPulmonary abnormalities are common in infants and young children with CF and relate to neutrophilic inflammation and infection with P. aeruginosa. Current models of care for infants with CF fail to prevent respiratory sequelae. Bronchiectasis is a clinically relevant endpoint that could be used for intervention trials that commence soon after CF is diagnosed after NBS.