Gamma-hydroxybutyric acid (GHB) as a natural component of the mammalian brain was first introduced in clinical anaesthesic practice more than 40 years ago. The drug was nearly forced from clinical practice because of its prolonged and variable duration of action. The results of recent clinical studies indicate a re-evaluation of GHB in various clinical fields. In the intensive care unit, GHB may be a favourable alternative to established drugs. The results of various clinical studies also suggest that GHB is efficacious in the treatment of alcohol withdrawal syndrome, and narcolepsy. GHB has been used successfully for short-term sedation in children. In addition, GHB has emerged as a street drug ("liquid ecstasy"). Overdose may lead to respiratory depression, coma, and even death. Chronic abuse itself may lead to severe withdrawal syndrome. The purpose of this article is to outline the neurophysiological, pharmacodynamic and pharmacokinetic characteristics of GHB, and to summarize the potential fields of use and misuse of GHB in clinical medicine and toxicology.