The acute respiratory distress syndrome (ARDS) is the devastating manifestation of the diffuse pulmonary inflammation that may occur following a wide range of life-threatening systemic illnesses. The rapid onset of inflammation and bilateral nonhydrostatic alveolar edema results in severe hypoxemia and reduced pulmonary compliance often mandating mechanical ventilation. The clinical features, radiology, and pathogenesis are reviewed in this article. The management of patients comprises primarily of ventilatory support while the lung injury resolves. The techniques of ventilatory support can propagate the lung injury and adversely affect outcome; the techniques are discussed in detail here. By contrast, pharmacotherapy has a less clear role in ARDS. Corticosteroids may be beneficial after the acute phases, whilst other anti-inflammatory agents have not proved beneficial. Mortality is determined primarily by the underlying trigger for ARDS, but is approximately 30–40%. Follow-up of survivors has demonstrated that lung function often improves considerably, whereas nonpulmonary morbidities persist even 12 months after discharge from the intensive care unit.