A 57-year-old man presented with palpitations, shortage of breath on exertion, and rapidly progressive scleroderma. On admission, a computed tomographic scan of his lung showed active interstitial pneumonia. We treated him with d-penicillamine and intravenous pulse methylprednisolone. After this treatment, severe abdominal pain, microangiopathic hemolytic anemia, thrombocytopenia, and progressive renal involvement appeared. We diagnosed him as having systemic sclerosis (SSc) complicated by thrombotic thrombocytopenic purpura. At postmortem, thromboses of capillaries, arterioles, and small arteries were found in several organs. As well as the differential diagnosis of SSc with thrombocytopenia, microangiopathic hemolytic anemia (MAHA), and renal involvement, we diagnosed scleroderma renal crisis (SRC), normotensive renal crisis (NRC), and SSc complicated by TTP. Typical SRC and NRC were excluded because his blood pressure was in the normal range without elevation of plasma renin activity or azotemia over his clinical course. Although distinguishing TTP from renal crisis is difficult, an evaluation of ultra-large multimers of von Willebrand factor (UL-vWF) concentration may be helpful in these situations.