Anti-Scl-70 antibodies are autoantibodies, which are immunoglobulins directed against their own intracellular and extracellular antigens, and are seen in a variety of autoimmune diseases. The antigen recognized by anti-Scl-70 antibodies is DNA topoisomerase I, a relatively specific antibody for systemic sclerosis. Positive anti-Scl-70 antibodies often indicate a poor prognosis, and patients with positive antibodies are prone to early and severe organ damage, such as renal failure, interstitial pneumonia, toe end finger lysis, and small bowel lesions. The rate of anti-Scl-70 antibody positivity is about 20%-60% in patients with limited scleroderma, 70%-76% in diffuse scleroderma, and about 12% in dermatomyositis or scleroderma, or overlap syndrome.