As a link in the studies on the transamination in the brain the author made a series of systematic studies on the transamination reactions in the brain of growing chick embryos, chicks at various stage of their growth, using 15 α-amino acids, 4 diamino acids, cysteic acid and α-ketoglutaric acid, and reported the result of such studies in previous papers. In the present experiment the transamination in the adult chicken brain was estimated in the similar way with the use of the same amino acids as in the previous experiment. 1. Of all the amino acids that showed the transaminase activity in the chick embryo and the chick brains at every developemental stage, lysine did not shows the activity in the adult chicken brains. 2. The grade of the transaminase activity of aspartic acid, isoleucine, β-alanine and cysteic acid is lower than the peak of the same observed in the eavly stage of the chick brains. As for the other amino acids with an exception of alanine which showed the greatest activity in the adult chicken brain, none showed the activity surpassing the maximum shown in the chick brains at every developemental stage. 3. Spcaking relatively and biochemically at least in the chicken brain the transamination reactions in the chicken brains, especially to that of the mouse brain.