Hydroxylysine has been found in extracts of the free amino acids from alfalfa root tissue. Its identification was based on chromatography on ion exchange columns with the isolated peak being in the same position as the synthetic amino acid. This peak increased in size upon co-chromatography with hydroxylysine. The 570/440 rnp absorbance ratio of the coloumd products formed with ninhydrin was the same as the synthetic hydroxylysine but greatly different from many other amino acids.