Abstract—Levels of free amino acids, profiles of polyribosomes, and rates of protein synthesis and degradation were examined in the brains of chicks fed toxic levels of galactose. The content of a number of amino acids were altered; alanine and leucine were most strikingly depressed, whereas levels of aspartate were elevated. Polyribosomal profiles were unaltered. There appeared to be no detrimental effect on protein synthesis as judged byin vivoincorporation of L‐[U‐14C]leucine and L‐[guanidino‐14C]arginine. Likewise, the half‐lives of proteins, measured by the loss of L‐[guanidino‐14C]arginine, were similar in experimental and control groups. In contrast, initial rates of incorporation of [3H]glucosamine into glycoproteins were enhanced. The effect was greatest in the microsomal fraction and typically 50 per cent greater than controls. Levels of free glucosamine and protein‐bound hexosamine were essentially unaltered in the gal