Skeletal keratan sulfates have been degraded by three independent techniques and the resultant, borohydride-reduced, disaccharides have been characterised by NMR spectroscopy. The ¹H and <sup>13</sup>C (where available) chemical shifts are reported for the following substances, where GalNAc-ol represents Nacetyl-galactosaminitol. GlcNAc-ol represents N-acetyl-glucosaminitol, GlcNAc(6S)-ol represents N-acetyl-glucosaminitol 6-O-sulfate and 2,5AnMan(6S)-ol represents 2.5-anhydro-D-mannitol 6-O-sulfate. (a) GlcNAc(6S)β(1-3)Gal-ol, isolated after keratanase (from Pseudomonas sp.) digestion. (b) Galβ(14)GlcNAc(6S)-ol and Gal(6S)β(1-4) GlcNAc(6S)-ol, the ¹H chemical shills have been reported previously [Brown, G. M., Huckerby, T. N., Morris, H. G., Abram, B. L. & Nieduszynski, I. A, (1994) Biochemistry 33, 4836-4846; Brown, G. M., Huckerby, T. N. & Nieduszynski, I. A. (1994) Eur: J. Biochem. 224, 281-308], GlcNAc(6S)β(1-6)GalNAc-ol, Galβ(14)GlcNAc-ol, Gal(6S)β(1-4)GlcNAc-ol, all isolated after keratanase II digestion, (c) Galβ(14)2,5AnMan(6S)-ol and Gal(6S)β(1-4)2.5AnMan(6S)-ol, isolated after hydrazinolysis and nitrous acid digestion. In addition, the model compounds Galβ(1-4)GlcNAc-ol and Galβ(1-6)GlcNAc-ol have also been examined by ¹H and <sup>13</sup>C NMR spectroscopy. The value of these data for microstructural analysis of keratan sulfate samples is discussed.