Growth assays were conducted to estimate the minimal dietary requirement levels of histidine, tryptophan, phenylalanine and tyrosine for the young kitten. Dietary concentrations of histidine and tryptophan of .30 and .15%, respectively, were found to support optimal kitten performance. A preliminary study of the total aromatic amino acid (TAAA) requirement indicated that no more than 1.20% TAAA (.60% phenylalanine + .60% tyrosine) is required by the kitten. Subsequent experiments revealed no decrease in growth rate when TAAA were reduced to 1.00% of the diet. At this level of TAAA, tyrosine could supply 50% of the requirement for TAAA.