Plasma amino acid concentration and Urinary exretion of free amino acids were measured in health female vegetarians(n=20, 19.9 $pm$0.43 years old ) and age-mateched imnivores(n=20, 21.9$pm$0.38years old) in Korean. differences infasting plasma amino acid concentrations and plasma aminogram pattern were not spectacular between the vegetarian and omnivore controls. Compared to the omnivores, vegetarians showed significantly lower plasma levels of methionine , phenylalanine, $alpha$-aminobutyrate, citrulline, phosposerine and tarurine, and significantly higher plasma concentrations of arginine, $alpha$-aminobutyrate, cirtrulline, phosphosierine and taurine, and significantly higher plasma concentrations of arginine, $alpha$-aminoadipate, asparagine, aspartate, glutamate and ornithine. Although these differences were statistically significant, they were all within the normal range (21~70% differences )for human adults. Most of the urinary amino acids (nmol/mg creatinine or $mu$mol/24 hr urine) were excreted to significantly lesser degree in vegetarians than was the case in omnivore controls. For almost every individual free amino acid, plasma concentration did not significantly correlate with urinary excretion level. These results indicate that vegetarians excreted less amino acids in their urine than did dominivores, most probably in an effort to maintain amino acid homeostasis to an altered dietary protein intake level and/or amino acid composition of their diets.