The effect of gamma-hydroxybutyric acid on alcohol consumption and alcohol craving in alcoholics was investigated in a randomized double-blind study versus placebo. Patients were treated as outpatients during a three month period either with gamma-hydroxybutyric acid (50 mg/kg/day, divided into three daily doses) or with placebo. Of the 82 alcoholics that entered the study, 71 completed it, 36 in the gamma-hydroxybutyric acid and 35 in the placebo group. Alcohol consumption was assessed by the subject's self report. At the 3rd month of treatment, 11 patients in the gamma-hydroxybutyric acid group referred to be abstinent and 15 referred controlled drinking; while in the placebo group only two and six patients referred abstinence and controlled drinking, respectively. Serum-gammaglutamyl-transferase activity correlated with the admitted alcohol consumption. Gamma-hydroxybutyric acid treatment decreased alcohol craving during the 3 months of treatment. Transient side effects were noted by six patients on gamma-hydroxybutyric acid and two on placebo. The results suggest that gamma-hydroxybutyric acid may be useful in the treatment of alcohol dependence.