Secondary acute myeloid leukaemia (AML) occurring after breast cancer is a rare long-term complication of the chemo- and/or radiation therapy required to treat breast cancer. The usually recognized curative option of these secondary AML includes courses of anthracycline-based chemotherapy followed by haematopoietic stem cell transplantation (HSCT). Cardiac dysfunction during AML treatment of these patients previously treated with anthracyclines for breast cancer has not been reported to date. We evaluated the evolution of cardiac function in seven patients treated with anthracyclines and/or autologous or allogeneic bone marrow transplantation for secondary AML occurring after breast cancer. All of the patients who received a cumulative anthracycline dose above the cardiac toxicity threshold developed cardiac symptoms during AML chemotherapy courses. Moreover, four of the five transplanted patients developed severe heart failure among which two were fatal. Thus, the risk of severe cardiac dysfunction after treatment of secondary AML following breast cancer must be taken in account as part of the therapeutic strategy of those patients. As discussed here, an accurate evaluation of risk factors, the use of sensitive detection tests and of cardioprotective drugs as well as that of non-cardiotoxic chemotherapy might decrease the occurrence and severity of this life-threatening complication.