The pathogenesis and etiology of systemic sclerosis (SSc) remain unknown, but the presence of several autoantibodies is recognized as one of its prominent features. The clinical significance of anti- DNA topoisomerase Ⅱ α antibody (anti- topo Ⅱ α Ab) remains unknown in Japanese patients with SSc. To determine the prevalence and clinical correlation of anti- topo Ⅱ α Ab in Japanese patients with SSc. Serum samples were obtained from 103 Japanese patients with SSc. Control serum samples were obtained from 43 healthy Japanese volunteers. Anti- topo Ⅱ α Abs were determined by enzyme linked- immunosorbent assay.IgG anti- topo Ⅱ α Ab levels were significantly increased in SSc patients (n=103) compared to normal controls (n=43; P<0.005). IgG or IgM anti- topo Ⅱ α Ab was detected in 19% (20/103) of SSc patients when absorbance values higher than the mean+ 2SD of control serum samples were considered positive. By contrast, IgG or IgM anti- topo Ⅱ α Ab was observed in only 7% (3/43) of healthy individuals. The presence of pulmonary fibrosis was more frequently detected in SSc patients with IgG anti- topo Ⅱ α Ab than those without the Ab (P<0.05). Moreover, % DLco and % VC were significantly decreased in SSc patients with anti- topo Ⅱ α Ab relative to those without the Ab (P<0.05 and P<0.01, respectively). The elevated levels of both erythrocyte sedimentation rate and C- reactive protein were also more frequently observed in SSc patients positive for IgG anti- topo Ⅱ α Ab (P<0.005). The results of the present study indicate that anti- topo Ⅱ α Ab represent one of the autoantibody specificities detected on SSc patients and may be regarded a serological marker of pulmonary fibrosis in Japanese patients with SSc. The pathogenesis and etiology of systemic sclerosis (SSc) remain unknown, but the presence of several autoantibodies is recognized as one of its prominent features. The clinical significance of anti- DNA topoisomerase II alpha antibody (anti- topo II α Ab) Japanese patients with SSc. To determine the prevalence and clinical correlation of anti- topo Ⅱ α Ab in Japanese patients with SSc. Serum samples were obtained from 103 Japanese patients with SSc. Control serum samples were obtained from 43 Japanese healthy volunteers. Anti- topo II α Abs were determined by enzyme linked-immunosorbent assay. IgG anti-topo Ⅱ α Ab levels were significantly increased in SSc patients (n = 103) compared to normal controls (n = 43; P <0.005) Topo α α Ab was detected in 19% (20/103) of the absorbance values ​​higher than the mean + 2SD of control serum samples were considered positive. By contrast, IgG or IgM anti- topo Ⅱ α Ab was observed in only 7 % (3/43) of healthy individuals. The presence of pulmonary fibrosis was more frequently detected in SSc patients with IgG anti- topo II α Ab than those without the Ab (P <0.05). Moreover,% DLco and% VC were significantly decreased in SSc patients with anti- topo II α Ab relative to those without the Ab (P <0.05 and P <0.01, respectively). The elevated levels of both erythrocyte sedimentation rate and C-reactive protein were also more frequently observed in SSc patients positive for IgG anti-topo II α Ab (P <0.005). The results of the present study indicate that anti- topo Ⅱ α Ab represent one of the autoantibody specificities detected on SSc patients and may be considered a serological marker of pulmonary fibrosis in Japanese patients with SSc.