Lung mechanics and pulmonary gas exchange studies were performed 6 and 12 months after the accident on 2 survivors of adult respiratory distress syndrome (ARDS) following near drowning in fresh water. The patients (25 and 29 years of age) were nonsmokers and neither had a history of lung disease. Immersion lasted 10 and 20 minutes, and assisted ventilation 19 and 34 days, respectively. The results show that lung mechanics returned to normal within 6 months after the onset of ARDS. Conversely, the ratio of dead space to tidal volume was increased significantly at rest and during exercise, and the ratio of capillary volume to alveolar volume was decreased in both patients. It is concluded that ARDS following prolonged near drowning in cold water causes late abnormalities of gas exchange probably related to decreased pulmonary capillary volume.