Public attention and research efforts are being driven by an ever- increasing understanding of the problems and magnitude of alcohol abuse, particularly its neurological consequences. Two out of three high school students report that they used alcohol during the previous month. This continuing source of potential abusers, plus 10 million alcohol-abusing adults, along with the several million abusers of other drugs, costs the people of the U.S. more than $200 billion in lost wages, health care, theft, and shortened life span. An intimate, detailed knowledge of the effects of alcohol on the biochemical reactions and neurological changes is critical in preventing or treating abuse. We must study the mechanisms of ethanol's effects on the neurological system at a cellular and systematic level to understand its actions. These include modifications of hormonal regulation and production with major functional consequences. The progress of research over the past decade is encouraging as we begin to summarize and evaluate in detail advances in understanding changes in the biochemistry and physiology caused by ethanol. This information will assist the researcher, clinician, and student in comprehending the complex changes caused by direct and indirect effects of single drugs at the cellular level.