The pulmonary function of 49 patients admitted to the trauma services of Parkland Memorial Hospital was studied primarily in terms of volume function and blood-gas exchange. The incidence of fulminant pulmonary failure was low (three out of 49 or 6%). There was no evidence that shock without concomitant direct pulmonary injury increased the incidence of significant pulmonary dysfunction. Factors that predisposed the injured patient to pulmonary dysfunction were (a) direct thoracic or pulmonary injury, (b) sepsis, (c) aspiration of gastric contents, (d) head injury, and (e) fat embolization. The factor that appeared to jeopardize the patient's normal lung function most was sepsis. Almost all septic patients had defects in compliance and failed to maintain an adequate arterial oxygen pressure. A substantial number of severely injured patients required mechanical respiratory assistance to maintain normal pulmonary function.