We present a case of a 74-year-old male, who had a relapse of minimal change nephrotic syndrome (MCNS) as the initial presentation of acquired hemophilia A. MCNS had been maintained in remission with prednisolone 10 mg for 15 years. In early December 2005, the patient developed edema of the right leg, was admitted to a local general hospital, and was diagnosed as having a relapse of MCNS based on massive proteinuria (urine protein 6.1 g/day). One week later, severe anemia (hemoglobin 4.4 g/dl) and acute renal failure (creatinine 2.0 mg/dl) developed, and a CT scan of the abdomen revealed a hematoma in the left iliopsoas muscle. He was referred to our hospital with bleeding tendency. Laboratory examination revealed prolonged APTT 80.5 seconds), reduced factor VIII activity (<1%) and thepresence of factor VIII inhibitor at a titer of 19 Bethesda units/ml, based on which he was diagnosed as having acquired hemophilia A. With recombinant activated FVII, hemostasis was obtained and prednisolone administration 60 mg/day (1 mg/kg) was started. Both the acquired hemophilia A and MCNS responded well to the treatment with prednisolone. Six weeks after initiation of the treatment, factor VIII inhibitor and urine protein disappeared. This patient is considered to be a rare case; to the best of our knowledge, this is the third report of acquired hemophilia A with nephrotic syndrome.