New born meconium contains at least a hundred oligosaccharides. In this study the isolation and characterization of the major constituents is described. The structure elucidation of 15 neutral and acidic oligosaccharides was carried out by methylation analysis, mass spectrometry and 360-MHz 1H-NMR spectroscopy. The results show that the oligosaccharides accumulating in human meconium are probably products of the catabolism of the O- and N-linked carbohydrate chains of glycoproteins. It is proposed that endo-N-acetyl-alpha-D-galactosaminidase, endo-beta-D-galactosidase and endo-N-acetyl-beta-D-glucosaminidase are involved in the production of these compounds.