1. The specific compound from Pneumococcus type 34 was isolated from capsular material by ion-exchange chromatography. This separated it from a substance with chemical and serological properties corresponding to those reported for C-substance. 2. The configuration of the two galactofuranosyl linkages in the repeating unit of S.34 was determined and the configurations previously assigned to the other glycosidic linkages were confirmed. 3. The dephosphorylated deacetylated repeating unit is thus O-β-d-galactofuranosyl-(1→3)-O-α-d-glucopyranosyl-(1→2)-O-β-d-galactofuranosyl-(1→3)-O-α-d-galactopyranosyl- (1→2)-ribitol.