Airway epithelial injury is thought to be a key event in the pathogenesis of chronic lung allograft dysfunction (CLAD). We investigated whether markers of epithelial activity and injury in bronchoalveolar lavage fluid (BAL) correlate with CLAD diagnosis and major CLAD phenotypes: bronchiolitis obliterans syndrome (BOS) vs restrictive allograft syndrome (RAS)-related phenotypes (including RAS, mixed phenotype, and all other patients with RAS-like opacities).