The acute respiratory distress syndrome (ARDS) is characterized by severe impairment of gas exchange and remains a challenge for modern intensive care medicine. The most common causes of ARDS are pneumonia and sepsis. The mortality in severe ARDS is as high as 50 %. The new definition of ARDS differentiates three levels of severity depending on the degree of hypoxaemia. The fundamental basis of therapy is to treat the underlying cause of ARDS. Furthermore, lung protective mechanical ventilation must be applied using low tidal volumes and limiting inspiratory pressures. Intermittent prone positioning can reduce mortality in severe cases of ARDS. In extreme, life threatening cases extracorporeal membrane oxygenation can stabilize gas exchange and serve as a bridge to recovery and means to enable lung protective ventilation.