The cathelicidin LL-37 is an antimicrobial and lipopolysaccharide neutralizing peptide, possessing pro-inflammatory, tissue repair and remodeling activities. Recent reports indicate that the progression of COPD might be connected with increased levels of LL-37. The numerous experimental data show the potential role of LL-37 in the response to the exposure to organic dust (containing lipopolysaccharide and microorganisms) which is one of the major COPD causative factors. This work strives to further prove the role of LL-37 in the development of COPD. A cross-sectional study was conducted in 30 farmers in the early stages of COPD according to GOLD, 36 healthy farmers and 16 healthy urban dwellers. Collection of induced-sputum samples and lung function testing were conducted before and after work. The quantification of the LL-37 in sputum samples was performed by mass spectrometry and radioisotope techniques. Levels of granzymes A and B, IL-8, IFN-gamma and TGF-beta₁ in sputum were measured by ELISA technique. Statistical analysis was conducted by Kruskal-Wallis and Mann-Whitney U tests. Significantly higher levels of LL-37 were observed in sputum samples from farmers with COPD compared to healthy individuals. The concentration of LL-37 in sputum from farmers was significantly higher compared to urban dwellers. The same was true for both granzymes A and B. The results of this study suggest that LL-37 and granzymes A and B may add to the development of COPD. The results suggest also their role in an organism's response to organic dust exposure.