This study hypothesizes that distinct biochemical and metabolic disturbances associated with liver injury may be related to specific cognitive changes in alcoholics. In 132 alcoholic men admitted to an alcohol treatment program, increases in gamma-glutamyl transferase (GGT) values were correlated with impairment in several measures of visuoperceptual and visuoconceptual functioning. The association between plasma levels of GGT and neuropsychological performance was independent of the relative contribution of other laboratory measures of liver injury and of alcohol consumption histories. These observations support the hypothesis that elevated levels of GGT are distinctly associated with neuropsychological deficits and suggest that possible mechanisms beyond severe hepatic dysfunction and alcohol consumption underlie cognitive deficits in alcoholics.