Background: Airway inflammation is associated with an increased expression and release of inflammatory reactants that regulate processes of cell migration, activation and degranulation. The purpose of this study was to quantify bronchial lavage (BAL) fluid and serum levels of chemokine (IL-8), secretory leukocyte protease inhibitor (SLPI), soluble intracellular adhesion molecules-1 (sICAM-1) and sCD14, as surrogate markers of inflammatory and immune response in asthma and chronic obstructive pulmonary disease (COPD) patients with similar disease duration time. Methods: Biomarkers in serum and BAL fluid from asthma (n = 13) and COPD (n = 25) patients were measured using commercially available ELISA kits. Results: We found that in asthma and COPD groups the concentrations of IL-8 and SLPI are significantly higher in BAL fluid than in serum, while levels of sICAM-1 and sCD14 in BAL fluid are significantly lower than in serum. Of these 4 measured biomarkers, only the BAL IL-8 was higher in COPD patients when compared to asthma (P < 0.05). In both groups, BAL IL-8 correlated with SLPI (r = 0.577, P < 0.01 and r = 0.589, P < 0.05, respectively). In patients with COPD the BAL sICAM-1 correlated with sCD14 (r = 0.576, P < 0.01), while in asthma patients BAL sICAM-1 correlated with FEV,/FVC (r= 0.418, P < 0.01). Moreover, in asthma patients the serum SLPI correlated with sCD14 (r=0.688, P < 0.01) and serum sICAM-1 negatively correlated with FEV1/FVC (r= -0.582, P < 0.05). Conclusion: Our findings point to the importance of selecting a correct biological fluid when analyzing specific biomarkers, and also show that of 4 measured biomarkers, only the BAL IL-8 was higher in COPD patients when compared to asthma. 2007 Published by Elsevier Ltd.