Abstract AIM OF THE STUDY Patients with congenital lung malformation (CLM) may present pulmonary inflammatory changes. However, little is known about the factors influencing local inflammation. Aim of this study was to evaluate the factors that may affect inflammatory changes in CLM. METHODS Patients with CLM operated upon between 2005 and 2021 were included. The grade of inflammation was defined with a purpose-made inflammatory score (IS) ranging from 0 to 5. The association of type of CLM and age at surgery with IS was analyzed. Results are means (standard deviation). MAIN RESULTS Data from 105 patients with CLM were collected, 56 had congenital pulmonary airways malformation (CPAM), 24 bronchopulmonary sequestration (BPS), and 25 congenital lobar emphysema (CLE). 91 patients (87%) had inflammatory changes. IS was 2.1 (1.5), 1.2 (1.0), and 1.3 (1.5) in CPAM, BPS, and CLE respectively (One-way ANOVA p=0.0101). CPAM showed a significantly higher IS as compared with BPS (p = 0.0242) and CLE (p = 0.0495). Age at operation significantly correlated to IS (r2=0.14; p <0.0001). Patients aged below 6 months at operation had lower IS [1.4 (1.2)] as compared to those over 6 months [2.0 (1.6)] (p =0.018). Age at operation significantly correlated with the IS in CPAM (r2=0.17; p=0.0016) and CLE (r2=0.47; p<0.0001) patients. CONCLUSIONS Patients with CLMs often present inflammatory changes in their lungs. Grade of inflammation significantly correlates with age at surgery and type of anomaly, with CPAMs having the highest grade. These findings support early resection in patients with CLM, especially in case of CPAM.