BACKGROUND: Posttraumatic acute respiratory distress syndrome (ARDS) is associated with prolonged mechanical ventilation and longer hospitalizations. The relationship between posttraumatic ARDS severity and financial burden has not been previously studied. We hypothesized that increasing ARDS severity is associated with incrementally higher health care costs. METHODS: Adults arriving as the highest level of trauma activation were enrolled in an ongoing prospective cohort study. Patients who survived 6 hours or longer are included in the analysis. Blinded review of chest radiographs was performed by two independent physicians for any intubated patient with PaO2:FIO2 ratio of 300 mmHg or lower during the first 8 days of admission. The severity of ARDS was classified by the Berlin criteria. Hospital charge data were used to perform standard costing analysis. RESULTS: Acute respiratory distress syndrome occurred in 13% (203 of 1,586). The distribution of disease severity was 33% mild, 42% moderate, and 25% severe. Patients with ARDS were older (41 years vs. 35 years, p < 0.01), had higher median Injury Severity Score (30 vs. 10, p < 0.01), more chest injury (Abbreviated Injury Scale score, ≥ 3: 51% vs. 21%, p < 0.01), and blunt mechanisms (85% vs. 53%, p < 0.01). By ARDS severity, there was no significant difference in age, mechanism, or rate of traumatic brain injury. Increasing ARDS severity was associated with higher Injury Severity Score and higher mortality rates. Standardized total hospital charges were fourfold higher for patients who developed ARDS compared with those who did not develop ARDS (US $434,000 vs. US $96,000; p < 0.01). Furthermore, the daily hospital charges significantly increased across categories of worsening ARDS severity (mild, US $20,451; moderate, US $23,994; severe, US $33,316; p < 0.01). CONCLUSION: The development of posttraumatic ARDS is associated with higher health care costs. Among trauma patients who develop ARDS, total hospital charges per day increase with worsening severity of disease. Prevention, early recognition, and treatment of ARDS after trauma are potentially important objectives for efforts to control health care costs in this population. LEVEL OF EVIDENCE: Economic and value-based evaluations, level IV.