A glycosaminoglycan with scleroderma-inducing effect was isolated and partially purified from the urine of patients with systemic scleroderma. The glycosaminoglycan was an N-sulfated glycosaminoglycuronan and its high total sulfate and 2,5-anhydromannose contents suggest that the glycosaminoglycan is a degradation product of heparin or polysulfated heparin sulfate. Furthermore, the composition of the above glycosaminoglycan was similar to that of the N-sulfated glycosaminoglycan which we observed previously in uninvolved skin of scleroderma.