Rationale: COPD is a chronic inflammatory disorder of the lung; yet the mechanisms that regulate this immune-inflammatory response are not fully understood. Objectives: We investigated whether IL-32, a newly discovered cytokine, was related to markers of inflammation and clinical progression in COPD. Methods: Using immunohistochemistry, expression of IL-32 was examined in surgically resected specimens from 40 smokers with COPD (FEV₁=39±4 % predicted), 11 smokers with normal lung function and 9 non-smoking controls. IL-32 was quantified in alveolar macrophages, alveolar walls, bronchioles and arterioles, and confirmed by molecular analysis. The levels of IL-32 were correlated with the cellular infiltrates, markers of inflammation and clinical data. Measurements and Main Results: Macrophage staining for IL-32 was increased in smokers with COPD compared with control smokers and non-smokers (p=0.0014 and p<0.0001) and similar differences were observed in alveolar walls (p=0.0004 and p=0.0005) and bronchiolar epithelium (p=0.004 and p=0.0009). This increase was also detected at mRNA level (p=0.007 vs control smokers and p=0.029 vs non-smokers) and was mainly due to non- isoforms. Moreover, IL-32 expression was positively correlated with TNF (p=0.004, r_s=0.70), CD8⁺cells (p=0.02, r_s=0.46), phospho p38MAPK (p<0.01, r_s=0.60) and negatively with FEV₁ values (p=0.004, r_s=-0.53). Conclusions: This is the first study to demonstrate increased expression of IL-32 in lung tissue of patients with COPD, where it was co-localized with TNF and correlated with the degree of airflow obstruction. These results suggest that IL-32 is implicated in the characteristic immune response of COPD, with a possible impact on disease progression.