Human dextran-antidextran-specific precipitates from individuals immunized with dextrans containing either one or two antigenic determinants, were analyzed for their content of various amino acids. Large differences in certain amino acids were found among α-(1 → 6)-specific antidextrans. Wide variations were also observed in antidextran fractions from a given individual specific for α-(1 → 6)- and α-(1 → 2)-linked glucose residues.