From the urine of patients with systemic scleroderma, we previously isolated a glycosaminoglycan, which could induce a scleroderma-like change in the skin of mouse. In the present work, the cell-mediated response to urinary glycosaminoglycans was examined by lymphocyte transformation test. The specific response was observed in lymphocytes of patients with scleroderma, when the above scleroderma-inducing glycosaminoglycan was added. By contrast, lymphocytes of patients with SLE or dermatomyositis and of normal persons hardly showed a response to this glycosaminoglycan. On the other hand, the glycosaminoglycans from normal urine could not stimulate lymphocytes of patients with scleroderma or healthy persons.