We report a case of microangiopathic hemolytic anemia(MHA)caused by metastatic breast cancer treated with weekly paclitaxel. A 58-year-old woman was diagnosed with metastatic breast cancer 2 years earlier. She was treated with various chemotherapy regimens and hormonal therapy, before being switched to fulvestrant 3 months earlier. She presented with severe anemia, and was diagnosed with MHA with bone marrow carcinomatosis following bone marrow biopsy. She was treated with weekly paclitaxel and recovered successfully. A subsequent biopsy showed that the bone marrow carcinomatosis had decreased. MHA due to breast cancer is rare and is associated with poor prognosis; however, rapid initiation of chemotherapy may be effective.