Basic scientists and clinicians have written numerous articles on the diverse causes of adult respiratory distress syndrome (ARDS). There is no specific diagnostic test for ARDS; the condition is characterized by interstitial lung edema, reduction in lung compliance, alveolar and small airway closure, decrease in functional residual capacity, and persistent hypoxia with increasing amounts of pulmonary blood flow coursing through nonventilated or poorly ventilated alveoli. Recent studies have emphasized the roles of macrophages and polymorphonuclear neutrophils in lung defense and injury. Advances in understanding the pathophysiology of ARDS have produced little significant change in the clinical management of the syndrome. There is no specific treatment for ARDS. The cornerstone of therapy is the early recognition and elimination of initiating factors such as sepsis. ARDS is not a single disease process, but appears to represent a final common pathway for the manifestation of a variety of lung injuries. The goal of therapy is to eliminate the predisposing condition and support the patient. New modes of ventilatory and pharmacologic therapy are presented.