Synthesized as anesthetic agent about fifty years ago, ketamine (Ketalar) has been supplanted by more attractive anesthetic agents with less adverse effects. Nevertheless, the potential of this drug, although often unknown by many practitioners, remains significant. Nowadays, ketamine is more and more used in the treatment and prevention of hyperalgesia and chronicisation of postoperative pain. Indeed, ketamine interacts with NMDA-receptors involved in spinal neuroplasticity and hyperexcitability responsible for these phenomena. Moreover, its efficacy to treat acute pain resistant to classic analgesics makes ketamine a very interesting and clinically-relevant drug for all practitioners facing this type of pain. This article reviews the clinical benefits of ketamine which has sometimes suffered from a negative reputation, but which possesses recently reconsidered wonderful pharmacological properties.