The impact of smoking on the peripheral airways, the determining field of respiratory functions in the lungs, is well known. Fifty two cases were included in the study; autopsy cases of non-cardiopulmonary related deaths with a smoking history, and cases with lung resection, known as smokers. Ten cases without a smoking history and a systemic disease were used as a control group at the histopathological examination. Parenchymal samples were taken from the central and peripheral airways (1st, 2nd, 3rd division) and from each lob. In addition, age, gender, amount and duration of smoking (package/year) were considered and histopathological changes of the lung are evaluated under the light microscope. The relations of all parameters to each other are evaluated and compared with the control group. On the distal airways with small diameter, Respiratory Bronchiolitis (RB) was determined in 14 (26.9%) cases, and Respiratory Bronchiolitis-associated interstitial lung disease (RB-ILD) in 16 (30.7%) cases. Two (3.8%) cases were diagnosed as Desquamative Interstitial Pneumonia (DIP). MMP-9, a matrix metalloproteinase known for its role in the development and repair of obstructive diseases of the lung related to smoking, and TIMP-1, an inhibitor, were used on the lung samples by means of immunohistochemical method. MMP-9 and TIMP-1 expressions of all cases were compared statistically with the existing pathological findings and the control group. MMP-9, TIMP-1 were expressed from the alveolar macrophages, endothelial and epithelial cells. Considering the MMP-9 and TIMP-1 density of alveolar macrophages, no statistically significant differences were found among the RB, RBILD and DIP case groups. However; despite of the significant MMP-9 expression of the DIP cases, TIMP-1 expression could not be determined. Compared to the control group, a more intensive and widespread positive reaction on MMP-9 was found in the alveolar macrophages. In conclusion, although there was no significant relation between the level and duration of smoking and the MMP-9 and TIMP-1 expressions, alveolar macrophages were found to be more important in lung damage related to smoking and the MMP-9 expression from these cells to be more intensive than the control group.