There has been much publicity regarding the use and abuse of gamma-hydroxybutyrate (GHB, "liquid ecstasy," or "GBH"). GHB has been found to be an endogenous compound but has also been used for various therapeutic applications in addition to illicit use, particularly as a dietary supplement, sexual adjunct, and "party drug." Toxicological analysis was performed using urine and/or plasma specimens from 27 nonfatal instances of suspected GHB intoxication in the United Kingdom between May 1998 and May 2003. GHB was detected in the plasma and urine, invariably with the additional presence of ethanol and other drugs of abuse (eg, amphetamines, cocaine, and morphine). GBL was also detected in the majority of urine specimens analyzed but was not detected in the plasma samples (<10 mg/L). The mean plasma and urine concentrations measured as "total GBL" were found to be 245 mg/L (range 86-551 mg/L) and 1732 mg/L (range 5-5581 mg/L), respectively. This is believed to be the largest compilation of nonfatal cases from the United Kingdom.