Glycoconjugates are distributed on the cell surfaces of some small-sized treponemes and have been reported to be com-pletely different from lipopolysaccharides. We separated a glycoconjugate fraction fromTreponema mediumATCC 700293, a medium-sized oral spirochete, to assess its immu-nobiological activities and elucidate the chemical structure of its polysaccharide part using phenol/water extraction, hydrophobic chromatography, and gel filtration.