Abstract Application of a single dose of 0.3 mmole amino-oxyacetic acid (AOA)/kg body wt intravenously results in a reversible alteration of most of the hepatocellular free amino acids in starved and well-fed rats. AOA does not influence exclusively the intracellular content of gluconeogenic amino acids. The content of histidine, arginine, methionine, valine, and isoleucine remains (nearly) unchanged. The aspartate content is diminished by more than 50%, whereas the levels of all the other amino acids are enhanced. Alanine increases 12 fold in starved rats after AOA application. Ornithine behaves differently from other amino acids. In contrast the plasma amino acid pattern is not affected at all. This may indicate, that in addition to liver other tissues may play an important role in regulation of plasma amino acid levels.