Using mice with chronic B(6) deficiency induced by B(6) deficient diet and other group of mice with acute B(6) deficiency induced by the intravenous injection of desoxypyridoxine, the author carried out quantitative analysis of free amino acids in the cerebral cortex of these animals, and obtained the following results. 1. In both groups with acute and chronic B(6) deficiency glutamic acid is markedly iucreased, but no significant change can be recognized in the quantity of γ-aminobutyric acid (GABA). 2. An increase of glycerophoethanolamine and phosphoethanolamine can be recognized in the group with B(6) deficiency. 3. In the group given the intravenous injection of desoxypyridoxine there can be observed an increase in alanine, glycine and valine. 4. Cystathionine is increased in the group with B(6) deficiency. 5. In comparing the results of assay of free amino acids in the B(6) deficient mouse brain with those of idiopathic human epileptic brain, there seems to be no direct connection between human idiopathic epilepsy and B(6) deficiency.