Introduction: Microangiopathic haemolytic anaemia is defined by evidence of haemolysis, schistocytes in the peripheral blood smear and a negative direct antiglobulin test and is usually associated with thrombocytopenia. It may be primary, like thrombotic thrombocytopenic purpura, or secondary, including systemic malignancy, which is very rare. It usually occurs at a terminal stage of cancer and it is associated with metastasis. Pathogenesis remains unknown. Case presentation: An 83 year- old- woman with diffuse metastatic right breast carcinoma, including bone marrow metastases suspicion, already submitted to mastectomy and palliative radiotherapy, presented with a two-week history of asthenia and dyspnoea. Routine analysis revealed acute normocytic normochromic, haemolytic anaemia, schistocytes in the peripheral blood smear, negative Coombs test and thrombocytopenia. Space-occupying lesions of the brain observed in CT scan were confirmed by RM to be brain metastasis. Because the initial diagnosis of cancer was already known, no further investigation was made, and cancer associated microangiopathic haemolytic anaemia was diagnosed. She was no candidate to antineoplastic treatment, so she received prednisolone for 4 days followed by a pulse regimen of 1g methylprednisolone daily for 3 consecutive days. Several transfusions were given, but there was little improvement of anaemia. The patient’s health condition continued to worsen resulting in her passing. Conclusion: It is very important to correctly diagnose cancer associated microangiopathic haemolytic anaemia in order to start the right treatment as soon as possible. Even today there exists no definitive treatment schedule for these patients. Systemic antineoplastic therapy is the best option to achieve clinical response. Despite this, the prognosis is extremely poor, most patients die within a few weeks after diagnosis