Acute lung injury is a syndrome with a diagnostic criteria base on hypoxaemia and a classical radiological appearance, with acute respiratory distress syndrome at the severe end of the disease spectrum. Its incidence is common, it is likely to exist outside the intensive care setting and therefore is a condition relevant to all clinicians. Genetically predisposed individuals are subject to environmental triggers which can be intra or extrapulmonary in nature. An inflammatory response causes damage to alveolar epithelial cells and vasculature, impairing gas exchange and can lead to multiple organ failure. Management centres around supportive care and treating the cause, but evidence supports use of low tidal volume ventilatory settings and conservative intravenous fluid strategies. Long term outcomes are related to neuromuscular, cognitive and psychological issues rather than pulmonary, and rehabilitation during recovery needs to focus on this.