In rapid sequence induction of anaesthesia in the emergency setting in shocked or hypotensive patients (e.g. ruptured abdominal aortic aneurysm, polytrauma or septic shock), prior resuscitation is often suboptimal and comorbidities (particularly cardiovascular) may be extensive. The induction agents with the most favourable pharmacological properties conferring haemodynamic stability appear to be ketamine and etomidate. However, etomidate has been withdrawn from use in some countries and impairs steroidogenesis. Ketamine has been traditionally contra-indicated in the presence of brain injury, but we argue in this review that any adverse effects of the drug on intracranial pressure or cerebral blood flow are in fact attenuated or reversed by controlled ventilation, subsequent anaesthesia and the greater general haemodynamic stability conferred by the drug. Ketamine represents a very rational choice for rapid sequence induction in haemodynamically compromised patients.