Eight adult patients with acute respiratory distress syndrome were treated with positive end-expiratory pressure (PEEP) ventilation. The results of detailed examinations of pulmonary function in these eight patients obtained after different periods of time following discharge from the respiratory care unit were analyzed to determine the degree of disturbances in pulmonary function. For comparison, examinations of pulmonary function were also performed on two patients who were treated with zero end-expiratory pressure ventilation. This follow-up study showed remarkably few abnormalities. Whe present, restrictive disturbances in pulmonary function, especially decreased static compliance and diffusing capacity, were found. No correlation was found between the pulmonary-function results of the eight patients and the duration of the PEEP treatment, nor between the results and the time interval between treatment at the respiratory care unit and the moment of the pulmonary function studies.