Recent studies have indicated that extracellular vesicles (EVs) may play a role in the pathogenesis of acute respiratory distress syndrome (ARDS). EVs have been identified as potential biomarkers of disease severity and prognosis in other pulmonary diseases. We sought to characterize the EV phenotype within bronchoalveolar lavage (BAL) fluid of patients with ARDS, and to determine whether BAL EV could be used as a potential biomarker in ARDS. BAL was collected from patients with sepsis with and without ARDS, and from esophagectomy patients postoperatively (of whom a subset later developed ARDS during hospital admission). BAL EVs were characterized with regard to size, number, and cell of origin. Patients with sepsis-related ARDS had significantly higher numbers of CD14/CD81 monocyte-derived BAL EV than patients with sepsis without ARDS ( = 0.015). However, the converse was observed in esophagectomy patients who later developed ARDS ( = 0.003). Esophagectomy patients who developed ARDS also had elevated CD31/CD63 and CD31/CD81 endothelial-derived BAL EV ( ≤ 0.02) compared with esophagectomy patients who did not develop ARDS. Further studies are required to determine whether CD31 BAL EV may be a predictive biomarker for ARDS in esophagectomy patients. CD14/CD81 BAL EV numbers were significantly higher in those patients with sepsis-related ARDS who died during the 30 days following intensive care unit admission ( = 0.027). Thus, CD14/CD81 BAL EVs are a potential biomarker for disease severity and mortality in sepsis-related ARDS. These findings provide the impetus to further elucidate the contribution of these EVs to ARDS pathogenesis.