Alcoholic patients were found to have increased urinary excretion of D-glucaric acid while drinking. The excretion of D-glucaric acid returned to normal after discontinuation of ethanol intake, and the increase in the excretion could be reproduced by the administration of ethanol. Determination of the urinary excretion of D-glucaric acid may be useful in detecting the ingestion of ethanol or drugs when this information is not available by other means.