Extracerebral organ dysfunction occurs frequently after severe brain injury and is associated with mortality and poor functional outcome. Cardiac and pulmonary complications are common, especially after aneurysmal subarachnoid haemorrhage. The exact causes of neurogenic myocardial dysfunction and pulmonary oedema after severe brain injury remain to be elucidated, but hyperactivity of the sympathetic nervous system and a systemic inflammatory response have both been implicated in its development. Hyponatraemia is the most frequent metabolic derangement seen after traumatic and non-traumatic brain injury. Both the syndrome of inappropriate antidiuretic hormone secretion and cerebral salt wasting have been described as the causal mechanism. In this review we will give an overview of the epidemiology, pathophysiology, and treatment options for neurogenic pulmonary oedema, cardiac dysfunction, and hyponatraemia after severe acute brain injury with a main focus on aneurysmal subarachnoid haemorrhage, and describe some insights regarding systemic inflammatory response syndrome in these patients. © 2012, Nederlandse Vereniging voor Intensive Care. All Rights Reserved.