Gamma-hydroxybutyrate (GHB) is a compound found in mammalian brain which meets many criteria of a neurotransmitter. GHB has been investigated as a tool for inducing absence (petit mal) seizures, for use as an anesthetic, and for treatment of narcolepsy, alcohol dependence and opiate dependence. Since 1990 GHB has been abused in the United States for euphoric, sedative and anabolic effects. Coma and seizures have been reported following abuse of GHB, but dependence liability has received little attention. The neuropharmacology, potential therapeutic uses and acute adverse effects of GHB are reviewed, followed by a case series of eight people using GHB. Adverse effects of GHB may include prolonged abuse, seizure activity and a withdrawal syndrome. This withdrawal syndrome includes insomnia, anxiety and tremor; withdrawal symptoms resolve in 3-12 days. GHB has the potential to cause a significant incidence of abuse and adverse effects. Prolonged use of high doses may lead to a withdrawal syndrome, which resolves without sequelae. Educational efforts should address the narrow therapeutic index, possible physical dependence and dangers of combining GHB with other drugs of abuse.