Cardiotoxicity is frequently present with anthracycline treatment. Most acute myeloid leukemia (AML) protocols use anthracyclines. Dexrazoxane has cardioprotective activity. The aim of this study was to evaluate cardioprotection of dexrazoxane in a prospective study. Fifty pediatric AML patients were treated with a Medical Research Council AML 10 modified protocol with dexrazoxane previous to any anthracycline dose. Cardiac function was evaluated at diagnosis, before every cycle, and every 6 months after the end of chemotherapy. Accumulative doses of anthracycline reached 424 mg/m2 (150 to 850 mg/m2). Forty-eight patients (96%) received a dose higher than 300 mg/m2. Twenty-eight percent had a grade of cardiotoxicity (24% grade 1 and 4% grade 2). Non 3 or 4 grade cardiotoxicity was seen. Cumulated anthracycline doses did not correlated with cardiotoxicity (P=0.815). The event-free survival was 53%, 15.7% died of disease, and 11.8% died free of leukemia. There is still not an agreement for the optimal method to reduce cardiotoxicity in children receiving anthracyclines. In our study, we could conclude that the use of dexrazoxane was effective cardioprotectant to allow a high-dose of anthracycline therapy. A randomized study is necessary to consolidate this asseveration.