N. Katsunuma has studied GOT isozymes from the standpoint of differences in their intracellular distributions and metabolic roles. Since TCA-cycle enzymes and oxidative phosphorylation are almost exclusively localized in mitochondria, while glycolytic or gluconeogenic enzymes are present in the cytoplasm, it is tempting to consider that cytoplasmic transaminase may play an important role in regulation of the glycolysis-gluconeogenic system. The present paper is on the role of the GOTs in gluconeogenesis. To test this, experiments were made involving liver perfusion and L-penicillamine(L-PeA) was used as a selective inhibitor of GOTs. The results show that the additions of aspartic and α-ketoglutaric acids caused marked increase in the concentration of glucose in the circulating blood and in glycogen synthesis in the liver, but glucose and glycogen synthesis from both acids were inhibited by addition of L-PeA and glucose synthesis from oxalacetic acid was not affected by L-PeA. On the other hand, as we have already reported, when animals were placed on gluconeogenetic state, only GOTs was markedly induced, while no induction of GOTM was observed. Thus, in summary, it is clear from perfusion and induction experiments that GOTs is of importance for gluconeogensis involving glucose or glycogen production from certain amino acids.