Ketamine, most commonly available as a formulation of ketamine hydrochloride, is a nonbarbiturate dissociative anesthetic agent. Categorized by chemical structure, ketamine is a derivative of cyclohexanone. Pharmacodynamically, ketamine interacts with several different receptor types, however its most significant interaction is the one with the N-methyl-Daspartate (NMDA) receptor, which is an antagonistic interaction. Ketamine is also known to interact with opioid mu receptors, which is why it posesses analgesic properties. Also known are the interaction of ketamine with sigma receptors, which are considered to result in a reduction of central senzitisation to pain, as well as the reduction of “wind-up” phenomenon (a phenomenon in which painful stimuli are serially amplified with continuous manipulation of the injured body part, for example in burn patients). The described properties make ketamine a potent analgesic in the emergency department. Furthermore, owing to the already mentioned numerous interactions with multiple receptor types, ketamine is also a potent sedation agent, a bronchodilator, enables maintenance of airway reflexes during procedural sedation, is a sympathomimetic and can terminate status epilepticus refractory to conventional medical therapy. Due to the described effects and properties, ketamine is an essential tool of the modern emergency physician. Emergency medicine literature is rife with publications that further clarify the usage of ketamine for existing indications or investigate new indications for its use and it is almost certain that ketamine will remain a versatile, reliable and easily available medication that emergency physicians will rely on for the management of a wide spectrum of emergencies.