We have investigated the interaction of 1,4 butanediol (1,4 BD) with ethanol and the involvement of the major metabolite of 1,4 BD, gamma-hydroxybutyric acid (GHB) in the ability of 1,4 BD to produce behavioral and EEG changes in rat as well as the toxic side effects of 1,4 BD. Behavioral, electrical, and biochemical studies in rats suggest that the effects of 1,4 BD are indeed mediated by GHB. Further, ethanol appears to block conversion of 1,4 BD to GHB. 1,4 BD however potentiates some of the behavioral effects of ethanol perhaps by a mechanism of action similar to that of other alcohols. Thus 1,4 BD appears to have two types of pharmacologic actions, one attributable to its conversion to GHB and the other an inherent property of the diol itself.