Determination of the amount of alcohol in the blood has now become an important feature in the medicolegal diagnosis of intoxication. It is usually impossible, however, to obtain blood for direct analysis; if it is obtained, the findings may be excluded as evidence in court.1Consequently an indirect determination of the concentration is now often made from saliva, from lung air and especially from urine.2 The use of the urine has some practical advantages. Under properly controlled conditions—but only under such conditions—the concentration of alcohol in the urine is an accurate index of the concentration of alcohol present in the blood at the time the urine is obtained. As the test is now often carried out by or for the police, serious discrepancies may occasionally occur, and the concentration of alcohol in the urine may differ widely from that in the blood. Consequently this testimony may jeopardize the