Twenty novel disulfated oligosaccharides were purified in nanomolar quantities from tracheo-bronchial mucous glycoproteins from a patient with cystic fibrosis via cleavage by alkaline borohydride treatment, followed by anion-exchange chromatography, size-exclusion chromatography, and high-performance liquid chromatography (HPLC). In addition to positive ion fast-atombombardment mass spectrometry (FABMS), proposed structures for the resulting purified disulfated oligosaccharides were also based on carbohydrate permethylation analyses, periodate oxidation, complete sequential exoglycosidase digestion, and parallel analysis of desulfated products. Sulfate esters were found to reside on C-3 or C-6 of terminal D-galactose and on C-6 of internal D-galactose or 2-acetamido-2-deoxy-D-glucose residues. For this group of oligosaccharides, ranging in size from tri- to undeca-saccharides and possessing linear, di- and tri-antennary forms, it was also observed that sulfate esters could be located on the same or on different branches and that branched oligosaccharides can possess sulfate esters on C-3 and C-6 of different terminal galactose residues within the same structure.