In a double-blind placebo-controlled trial, gamma-hydroxybutyric acid (GHB) (25 mg/kg orally) suppressed most of the withdrawal symptomatology in 14 heroin addicts and 13 methadone-maintained subjects. The GHB effect was prompt (within 15 minutes) and persisted for between 2 and 3 hours. Subsequently, the same patients received GHB in an open study every 2 to 4 hours for the first 2 days and 4 to 6 hours for the following 6 days: most abstinence signs and symptoms remained suppressed and patients reported felling well. Urine analysis failed to detect any presence of opiate metabolites. No withdrawal symptomatology recurred after 8 days of treatment when GHB was suspended, and patients were challenged with an intravenous injection of 0.4 mg naloxone. The results indicate that GHB may be useful in the management of opiate withdrawal.