In blood-group H substance from pig stomach cell linings, carbohydrate structures are known to occur which are O-glycosidically linked via GalNAc to Ser or Thr of the polypeptide backbone. They have in common the Gal(beta 1 leads to 3)GalNAc core unit, which bears one or more N-acetyllactosamine branches. The latter are terminated either by Fuc in (alpha 1 leads to 2) linkage or by GlcNAc in (alpha 1 leads to 4) linkage to Gal. Both terminal sequences are considered to be porcine blood-group H antigenic determinants. Employing 500-MHz 1H-NMR spectroscopy, the spectral features of the oligosaccharide-alditols corresponding to these chains were established. Insight could be gained into the microheterogeneity displayed by some of the alditol fractions as to the distribution of the terminating Fuc and GlcNAc residues over the various branches. Such information can hardly be obtained using other approaches.