Background: Pneumonia mortality rate is up to 20%, while the intensive care unit (ICU) rate reaches 50%. Pneumonia mainly targets alveolar epithelial cells and the epithelial barrier which contains glycocalyx. Syndecan (SDC) is a type of proteoglycan that is found on the surface of cells and is part of the glycocalyx. The alveolar endothelium and epithelial cells exhibit the expression of SDC-1 in bronchoalveolar lavage (BAL) fluid when inflammation occurs. Aim: This study investigates the release of SDC-1 to demonstrate the breakdown of the glycocalyx barrier in the alveolar epithelium of patients with pneumonia. Furthermore, it aims to ascertain the impact of this harm on ICU mortality. Material and Methods: A total of 24 patients with pneumonia on mechanical ventilators in the ICU were included in this cross-sectional analytical observational study. Alveolar epithelial SDC-1 levels retrieved in BAL by fiber-optic bronchoscopy (FOB) and pneumonia severity index (PSI) scoring were assessed. Results:Spearman’s rho correlation test shows strong positive correlation between alveolar epithelial SDC-1 level and PSI score (p < 0,001; r = 0,739). However, Mann-Whitney U test shows no significant correlation between alveolar epithelial SDC-1 level and mortality in ICU (p = 0,582). Conclusion: Higher alveolar epithelial SDC-1 level correlate positively with PSI score while it does not show significant correlation with ICU mortality.