Hydroxyaspartic acid has been identified in extracts of the free amino acids from field grown alfalfa and clover root tissue. It was identified by chromatography and co-chromatography on ion exchange columns and the amount of ammonia liberated on periodate oxidation. It occurs in these legume root tissues in amounts ranging from 06-2 ,umoles/g of dry root tissue. This is much higher than the concentration of some of the more common amino acids.