In its natural environment, which consists of fermenting plant materials, the fruit fly Drosophila melanogaster encounters high levels of ethanol. Flies are well equipped to deal with the toxic effects of ethanol; they use it as an energy source and for lipid biosynthesis. The primary ethanol-metabolizing pathway in flies involves the enzymes alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH); their role in adaptation to ethanol-rich environments has been studied extensively. The similarity between Drosophila and mammals is not restricted to the manner in which they metabolize ethanol; behaviors elicited by ethanol exposure are also remarkably similar in these organisms. Flies show signs of acute intoxication, which range from locomotor stimulation at low doses to complete sedation at higher doses, they develop tolerance upon intermittent ethanol exposure, and they appear to like ethanol, showing preference for ethanol-containing media. Molecular genetic analysis of ethanol-induced behaviors in Drosophila, while still in its early stages, has already revealed some surprising parallels with mammals. The availability of powerful tools for genetic manipulation in Drosophila, together with the high degree of conservation at the genomic level, make Drosophila a promising model organism to study the mechanism by which ethanol regulates behavior and the mechanisms underlying the organism's adaptation to long-term ethanol exposure.