PURPOSE: Congenital diaphragmatic hernia is an uncommon cause of respiratory distress in newborn infants and initially characterized by severe restrictive lung dysfunction. The problems of initial management and short-term prognosis have been well reported. However, long-term outcome has not been clearly defined. We studied the late respiratory problems and lung function after repair of congenital diaphragmatic hernia. METHODS: Fourteen patients who had repaired congenital diaphragmatic hernia at Ajou University from January 1995 to August 2009 were included for this study. RESULTS: Six cases (42.8%) showed late respiratory problems including recurrent bronchiolitis, pneumonia, bronchial asthma and prolonged chest wall retraction. Lung perfusion scan showed a perfusion defect in 1 case whose mean perfusion to the operated side was lower than the unaffected lung. Pulmonary function test showed restrictive pulmonary insufficiency in 2 cases. The cases with the late pulmonary problems revealed more restrictive pulmonary insufficiency compared to those without. The prolonged time taken to surgery from diagnosis, prolonged intensive care time, and prolonged ventilator care after surgery have been found to be the determinants of the impaired pulmonary functions. CONCLUSION: In summary, a portion (about 20%) of the patients with congenital diaphragmatic hernia showed impaired pulmonary function, even when they had no apparent respiratory symptom or limitations of activities. From these results, regular long-term follow-up of lung function is required postoperatively in patients with congenital diaphragmatic hernia, especially in cases with the aforementioned risk factors.