Etomidate is a sedative–hypnotic chemically unrelated to other induction agents. The pharmacological and safety profile of etomidate offers many advantages for induction during rapid sequence intubation (RSI) in the emergency department (ED). Its onset of action is within 5 to 15 seconds, and its duration of action is 5 to 15 minutes. Unlike thiopental, propofol, midazolam and, to a lesser extent, ketamine, etomidate has minimal respiratory or cardiovascular effects and can be safely used in patients with hemodynamic instability or cardiac ischemia. Etomidate is cerebroprotective, with the ability to decrease intracranial pressure and maintain cerebral perfusion, making it an ideal agent for patients with head injuries. Of the currently available induction agents, etomidate offers the most favourable safety profile and is the least likely to produce adverse effects in patients with unknown or untreated medical conditions. Etomidate may cause pain on injection, myoclonic movements on induction, hiccups, nausea and vomiting. Transient adrenal suppression has been reported, but not to a clinically significant degree, after single induction doses for ED RSI. Etomidate has been well studied in the ED and should be adopted for RSI in specific ED patient groups.