AbstractGlutamic acid, glutamine, GABA, aspartic acid, and alanine have been determined throughout the ontogenetic development of the rabbit visual system, i.e., occipital cortex, superior colliculi, lateral geniculate bodies, and retina. At 11 days of age, when the rabbits' eyes were opening, many of the amino acids had decreased significantly in the individual parts, and then later increased to more mature levels. The amino acid level appeared to be fully developed by 30 days of life with glutamic acid having the highest concentration in the cortical area and GABA in the subcortical ones.