It may appear surprising in view of the spectacular advances made in biology in recent years that the chemically simple process, the oxidation of ethanol via acetaldehyde to acetate, is still not sufficiently known with regard to biochemical mechanisms, localization in the body, and effects on the metabolism of other substances. In 1919, Mellanby showed that the concentration of ethanol in the blood of human subjects after a single dose decreased in a linear way for many hours (1). Widmark later made a careful study of the absorption, distribution and elimination kinetics of alcohol, which led to the extensive use in Scandinavia of blood alcohol determinations for forensic purposes (2). Lundsgaard showed that the liver is by far the most important organ for elimination of ethanol (3). Moreover, he faced the fact that ethanol is a nutrient which on average provides a considerable proportion of the energy needed for the human body, 10–15% in the case of Danish population. He also pointed out that only about 40% of the total metabolism can be met by the oxidation of alcohol. In the last decade or so interest in various aspects of alcohol metabolism has been increasing, partly because of the practical importance, but also because it involves some biochemically fundamental problems.