PURPOSE: To investigate long-term cardiac sequelae associated with anthracycline use in adjuvant chemotherapy of patients with early breast cancer. PATIENTS AND METHODS: All 1,000 patients from three prospective trials of adjuvant chemotherapy containing doxorubicin (n = 637, median total dose of 294 mg/m²) or not containing the anthracycline (cyclophosphamide, methotrexate, and fluorouracil [CMF] regimen alone, n = 363) were analyzed for the relative incidence of congestive heart failure (CHF) and myocardial infarction (MI) during 14 years of follow-up. The 462 women continuously free of disease as of February 1996 were recalled, and 355 consented to undergo evaluation including 12-lead ECG and cardiac ultrasound with determination of left ventricular ejection fraction (LVEF) to assess the relative incidence of abnormalities in long-term survivors. RESULTS: Among the 1,000 patients, there were six cases of CHF and three cases of MI. Cumulative cardiac mortality accounted for 0.4% (doxorubicin-treated = 0.6%; CMF-treated = 0). Eighteen (5%) of the 355 patients undergoing cardiac evaluation after median 11 years of follow-up presented systolic dysfunction as defined by pathologic (< 50%, n = 8) or borderline (50% to 55%, n = 10) LVEF. Systolic dysfunction was higher in doxorubicin-treated (15 of 192; 8%) than in CMF-treated patients (three of 150; 2%). Breast irradiation had a significant impact on the occurrence of early CHF (four of 116; 3%), but not on systolic dysfunctions. CONCLUSION: At longer than 10 years of follow-up, the use of doxorubicin at a total dose commonly applied in regimens of adjuvant chemotherapy does not lead to cardiac clinical sequelae that counter-balance the benefit of treatment in patients with operable breast cancer who may be cured of their disease.