Ethyl glucuronide (EtG) is a direct ethanol metabolite. The presence of EtG in urine can be used as a laboratory test to detect recent alcohol consumption. Several earlier studies in humans and in rats revealed that the same amount of ethanol ingested at different concentrations results in different blood ethanol concen- trations. The effect of different concentrations of ingested ethanol on the resulting EtG levels in urine was tested in WHP rats. The EtG concentration was also measured in rat hair. A significant (p < 0.05) decrease in the total amount of urine EtG after administration of the higher concentration (50%) ethanol solution as compared to 30% ethanol at the same dose of ethanol (3 g/kg) was observed. Median EtG concentration in rat hair of 1.5 ng/mg (range: 0.7-2.3 ng/mg) was observed. Our results demonstrate that EtG production and excretion in WHP rats is dependent on alcohol concentration administered orally. EtG levels in hair closely reflect the fate of EtG in the rat.