We herein report a case of systemic sclerosis associated with microscopic polyangitis. The patient was a 54-year-old woman, who was diagnosed to have systemic sclerosis at a hospital in 1992, but she did not receive any medical treatment. She had been suffering from pyrexia, paresthesia and muscle weakness of both lower limbs since the beginning of 2001, and was introduced to our hospital. She showed hardened skin extending from her fingers to upper arms, weakness in both lower limbs and livedo reticularis. Her laboratory test showed WBC 11, 600/microliter, CRP 6.63 mg/dl, CH 50 24 U/ml, anti Scl-70 antibody 90.1 index, and MPO-ANCA 281 EU, but no impaired renal function was recognized. Chest computed tomography showed interstitial pneumonia while necrotising vasculitis of the right sural nerve was found in a biopsy specimen. Based on these findings, we diagnosed her to have systemic sclerosis accompanied with microscopic polyangitis (MPA). She received steroid treatment after the diagnosis was made, and her symptoms and the laboratory findings thereafter immediately improved. Many cases have been reported to have ANCA positive systemic sclerosis among patients with systemic sclerosis that are complicated MPO-ANCA-related vasculitis. However, since our patient demonstrated necrotising vasculitis in a sural nerve biopsy and no evidence of an impaired renal function, we diagnosed her to have systemic sclerosis complicated with MPA instead of ANCA positive systemic sclerosis. The pathological state of this patient thus seemed to be different from that of ANCA-positive systemic sclerosis. We concluded that this patient had both systemic sclerosis and MPA. It is therefore important to note that some patients who have been reported to have ANCA-positive systemic sclerosis may also have systemic sclerosis complicated with MPA.