Abstract 1. (1) An augmented yield of acidic glycosaminoglycans, both digested with and resistant to chondroitinases, was observed in 24-hour urine of a patient with Weber Christian disease. 2. (2) The elevation of the excreted acidic glycosaminoglycans was reflected as an increase of acidic glycosaminoglycans eluted with lower concentrations of NaCl from Dowex 1-X2 columns. This finding correlated with the elevated proportion of the non-sulfated disaccharide subunit derived from undersulfated chondroitin sulfate isomers. 3. (3) Enzymatic assay of chondroitin sulfate isomers in the disease indicated that the disulfated disaccharide derived from oversulfated chondroitin sulfate was clearly found at the higher molecular weights by gel filtration on Sephadex G-100. The proportion of the 4-sulfated disaccharide to the 6-sulfated disaccharide was relatively greater in the disease in comparison to normal subjects. 4. (4) The analytical results from gel filtration indicated that depolymerization of urinary acidic glycosaminoglycans and glycopeptides occurs in the disease. The grade of the depolymerization of acidic glycosaminoglycans was associated with the degree of desulfation of chondroitin sulfates in terms of the disaccharide subunit level. 5. (5) Electrophoretic separation of the fractionated urinary acidic glycosaminoglycans on gel filtration revealed that heparan sulfates accounted for the major glucosaminoglycans with higher molecular weights, which were also eluted at lower NaCl concentrations from the Dowex column. On the other hand, chondroitin sulfates accounted for major galactosaminoglycans with lower molecular weights, which were eluted at the relatively higher NaCl concentrations on the Dowex column.