The degree of galactosamine N-acetylation, iduronic acid composition, and total uronic acid/hexosamine ratios of the three dermatan sulfates of human skin, DS18, DS28, and DS35 (M. O. Longas et al. (1987) Carbohydr. Res. 159, 127-136), were determined by Fourier transform, proton nuclear magnetic resonance (FT 1H NMR) spectroscopy. Analysis of DS of varying ages was conducted at 400 MHz and 60 degrees C. Chemical shifts for H-1, H-2, H-4, and H-5 of L-IdUA were independent of those for the respective protons of D-GalNAc and D-GlcUA. The resonance intensities of H-1 and acetamido methyl protons of D-GalNac did not display the expected 1:3 ratios. Therefore, their integration values were employed to estimate the percentage N-acetylation (N-CH3/3 H-1) which was corroborated chemically. The L-IdUA content, relative to total uronic acid, was calculated from signal intensities of H-1 of L-IdUA and D-GlcUA and ascertained by quantitative chemical methods. Total uronic acid/hexosamine ratios were determined from both 1H NMR spectroscopy and chemical analyses. The data show the following N-acetylation (N-CH3/3 H-1) of galactosamine in DS:DS18, 61-72% between 17 and 60 years, unaffected by senescence; DS28, 78-86% with no age-related trend; DS35, 101% at 19 years. Furthermore, in all ages investigated, the percentage (wt/wt) L-IdUA relative to total uronic acid was 42-44% for DS18 and 37-40% for DS28. At age 19 years, DS35 had a 29% (wt/wt) L-IdUA. The total uronic acid/hexosamine ratios for DS18 and DS28 varied from 1.40:1.0 to 1.70:1.0 irrespective of age.