Urine, amniotic fluid and ascitic fluid samples of galactosialidosis patients were analyzed and structurally characterized for free oligosaccharides using capillary high-performance anion-exchange chromatography with pulsed amperometric detection and online mass spectrometry. In addition to the expected endo-b-N-acetylglucosaminidase-cleaved products of complex-type sialylated N-glycans, O-sulfated oligosaccharide moieties were detected.