A 57-year-old man had been suffering from dermatomyositis and systemic sclerosis presenting interstitial pneumonia since Jan, 2004. On February 2, 2005, he was admitted to our hospital because of thrombocytopenia, hematuria and proteinuria continuing from January, 2005. Hemolytic anemia and thrombocytopenia progressed, and fragmented red cells were present in peripheral blood on the 11th hospital day. Thrombotic microangiopathy (TMA) was diagnosed and he was treated with plasma infusion and methylprednisolone pulse therapy. Bloody sputum and hypoxia were observed, and HRCT of the chest on the 12th hospital day revealed multiple infiltrates and consolidations throughout all lung fields. His hypoxia was exacerbated and he was placed on a ventilator on the 13th hospital day. Bronchoscopic examination showed bleeding from both bronchi and he was diagnosed with complicating diffuse alveolar hemorrhage. He died of progressive respiratory failure. TMA and diffuse alveolar hemorrhage are rare but important complications of dermatomyositis and systemic sclerosis and need special care.