Anthracyclines, potent cytotoxic agents used to treat a broad spectrum of malignancies, are limited in their use by an attendant risk of cardiotoxicity. Malignancies affect all age ranges, and anthracyclines are used in all age ranges, thereby exposing a broad population of patients to the development of heart disease. For some treated patients, anthracyclines affect cardiac muscle, resulting in cardiomyopathy. The type and degree of cardiomyopathy, as well as when during or after treatment the condition occurs, are dependent on what risk factors are present. Age is a major risk factor. Children and adults may develop restrictive and dilated cardiomyopathy. The length of subsequent survival and amount of subsequent somatic growth may influence late anthracycline-associated cardiac outcome. Early cardiotoxicity, occurring during or within 1 year of completion of treatment, is the largest risk factor for the development of late cardiotoxicity, which occurs beyond a year of completion of treatment. Risk factors, which appear to be specific for early cardiotoxicity in children, include black race, trisomy 21, and the use of amsacrine therapy after anthracycline therapy. More cardiotoxic effects are seen in survivors of childhood cancer, the longer from completion of treatment a patient is followed. Cumulative as well as peak anthracycline doses affect adults and children alike, and cardiotoxicity occurs early and late. In adults, left ventricular contractility is affected by anthracyclines. Children may manifest impairment of left ventricular contractility and increased afterload due to thinning of left ventricular walls. Patients with an early presentation of depressed left ventricular contractility are likely to show progression of cardiac disease with time. In addition, female gender appears to affect early and late cardiotoxicity in both adults and children, although this risk factor has been described predominantly in the survivors of childhood cancer. Thus, although anthracycline chemotherapy has improved overall survivorship of patients with cancer, there is a significant risk of cardiotoxicity associated with this class of drugs.