Metronidazole has a favorable clinical effect in acute alcohol withdrawal, produces objectively a decreased tolerance to alcohol at the beginning of therapy and subjectively a loss of desire for alcohol after more prolonged administration. Different possible mechanisms of metronidazole action were discussed. Since metronidazole inhibits alcohol dehydrogenase, the inhibited transformation of alcohol to acetaldehyde might be one factor in the different effects of the drug described. Metronidazole has an alcohol in its chemical structure and the drug may occupy certain cellular receptors which were formerly activated by alcohol in the chronic drinker, consequently removing the physical need to drink. This may be conceptualized as a structural blockade by this drug on the cellular receptor sites of alcohol.