Ketamine is an N-methyl-D-aspar tate receptor antagonist that has been in clinical use in the USA for over 30 years. Its ability to provide profound analgesia and amnesia while maintaining spontaneous respiration makes it an ideal medication for procedure-related pain and trauma. In the chronic pain arena, its use continues to evolve. There is strong evidence to support its short-term use for neuropathic and nociceptive pain, and conflicting evidence for preemptive analgesia. Its potential ability to prevent 'windup' and, possibly, 'reboot' aberrant neurologic pathways in neuropathic and central pain states has generated intense interest. However, the long-term use of ketamine for chronic neuropathic pain is limited by its side effect profile, and is largely anecdotal. More research is needed to better ascertain its long-term efficacy and side effects, to determine the ideal candidates for sustained treatment and to develop means of exploiting the antinociceptive properties of ketamine while minimizing the adverse effects.