Introduction: Congenital lung malformations (CLM) are rare disorders and surgical intervention is the definitive treatment. Our aim is to evaluate the long term lung function of patients with CLM after surgery compared to healthy children. Methods: 16 children with CLM (M/F: 9/7) and 30 age-matched healthy controls (M/F: 13/17) were included in the study. Demographic data was recorded and both groups were compared by Spirometry and nitrogen based Lung Clearance Index (LCI). Results: Mean age of the patients was 12.0 ±5.4 years old. Mean Forced expiratory volume in 1 second (FEV₁), Forced vital capacity (FVC), FEV₁/FVC and Forced expiratory flow between 25% and 75% of force expiration (FEF_25-75) %pred was, 86.68 ±16.65, 88.00 ±14.58, 97.44 ±9.89 and 79.00 ±26.41 respectively in patients group. Patients with CLM, had significantly lower values in FEV₁, FVC, FEF_25-75 values than healthy controls (p:0.002, p:0.007, p:0.045). While mean LCI_2,5% value in patients’ group was 8.33 ±1.52, it was 7.28 ±0.80 in healthy controls (p:0.023). Strong inverse correlation between LCI and FEV₁, FEV₁/FVC was detected in patients’ group (p: 0.023 r: -0,581, p: 0.017 r: -0,606 respectively). Conclusion: Current study revieled that patients operated due to CLM have impairment in the pulmonary function compared to healthy children in long term follow-up and LCI may be more accurate detecting airway diseases earlier than spirometry.