Gamma-hydroxybutyrate (GHB), a compound found in the mammalian brain, meets many criteria of a neurotransmitter. Experimentally, GHB has been used as a model for petit mal epilepsy; clinically it has been used as a general anaesthetic, to treat certain sleep disorders and alcoholism. Lately GHB has been abused for its euphoric, sedative and anabolic effects. Coma and seizures following abuse of GHB have been reported, but dependency has received little attention. Adverse effects of GHB include seizure activity and a withdrawal syndrome characterised by insomnia, anxiety and tremor. The present paper reviews the neuropharmacology, potential therapeutic uses and acute adverse effects of GHB, together with a presentation of three cases.