Acute respiratory distress syndrome (ARDS) is a type of acute diffuse lung injury associated with a predisposing risk factor, characterized by inflammation leading to increased pulmonary vascular permeability and loss of aerated lung tissue. The hallmarks of the clinical syndrome are hypoxemia and bilateral radiographic opacities, associated with several physiological derangements including: increased pulmonary venous admixture, increased physiological dead space, and decreased respiratory system compliance. No pharmacologic treatments aimed at the underlying pathology have been shown to be effective, and the management remains supportive. Lung-protective mechanical ventilation remains the key supportive intervention in ARDS patients, although extracorporeal lung support may extend its role in the near future.