We have studied 60 pediatric patients with different neoplastic diseases, treated with anthracyclines. We have followed them clinically and echocardiographically to detect the cardiotoxicity due to anthracyclines and the enhanced factors promptly. We have detected a more important incidence of cardiomyopathy in patients with non-Hodgkin's lymphoma, osteosarcoma and neuroblastoma despite cumulative doses under 550 mg/m2 of anthracyclines. The 2 first groups were treated with high doses of cyclophosphamide and methotrexate, and neuroblastomas with melphalan. The anthracyclines cardiotoxicity is evaluated around 5% in patients treated with doses under 550 mg/m2, and is increased in case of previous or simultaneous aggressive therapy. Continued echocardiography enables a premature detection of cardiotoxicity in these high risk patients.