Branched-chain amino acids (valine, leucine and isoleucine) and their nitrogen-free analogues, the branched-chain ketoacids, have become a subject of rapidly increasing interest in recent years. Biochemical studies of these compounds have now established that they have a protein-anabolic effect, and that they may play a regulatory role in protein synthesis. Clinical studies have established that these compounds alone, or mixures of these compounds with other essential amino acids or nitrogen-free analogues thereof, may be effective therapeutic agents in a variety of disorders, including states of protein intolerance such as portal-systemic encephalopathy, chronic renal failure, and urea cycle enzyme defects. Amino acid mixtures containing predominantly branched-chain amino acids or branched-chain ketoacids also seem to be effective in promoting protein anabolism in patients. The mode of action of these agents in these disorders has not been clarified, but is in all probability related to their biochemical effects now being intensively studied. Furthermore, many aspects of their metabolism in the body and the regulation of their plasma concentrations appear to be unique. Owing to the fact that biochemists studying these problems and clinicians attempting to use these compounds therapuetically have had little contact, the time seems propitious for meeting designed specifically with the intent to bring these two groups together to exchange ideas and information.