Cardiotoxicity is a potential adverse effect of anthracycline (A) therapy. Radiotherapy (XRT) may also cause a variety of cardiac complications. The purpose of the present study was to evaluate these cardiac side-effects in children and adolescents treated for cancer. We assessed the cardiac status of 91 patients, divided into three groups: Group A (n = 53) had anthracyclines at a mean cumulative dose of 410 mg/m2, group A+XRT (n = 26) had both chest irradiation (XRT) and A (mean 360 mg/m2), and group XRT (n = 12) had XRT alone. The patients differed from the controls in both systolic and diastolic indices of myocardial function. In echocardiography, the left ventricular (LV) contractility was abnormal in 32% in group A, in 50% in group A+XRT, and in 8% in group XRT. In radionuclide cineangiography, the LV ejection fraction was subnormal in 19% in group A, in 24% in group A+XRT, and in 1 patient in group XRT. A higher cumulative dose of A predicted decreased contractility. Treatment with A and/or XRT often leads to cardiotoxicity. Although in most cases this cardiotoxicity seems to be mild and subclinical, the long-term clinical sequelae merit further evaluation.