We reported a case of DIC who was administered FEC90 (5-FU 1,000 mg/body, epirubicin 170 mg/body, cyclophosphamide 1,000 mg/body) for advanced breast cancer. A 55-year-old woman was referred to our hospital with lumbago. There was a huge tumor in her left breast (10x10 cm) and bone scintigraphy showed multiple bone metastasis, so she was treated with FEC90. Before the third course, DIC occurred. The patient was then treated with FOY and heparin, and the DIC was resolved. We think the DIC of this case was related with tumor lysis syndrome. Febrile neutropenia has been occasionally emphasized during chemotherapy, but due care must be taken for lymphocyte depletion during treatment.