To compare dose-intensified epirubicin monotherapy with a standard sequential regimen, patients with primary breast cancer and > or =10 involved axillary nodes were randomised to either four 21-day cycles of epirubicin 120 mg/m(2) (E120; n=202) or four 21-day cycles of epirubicin 90 mg/m(2) plus cyclophosphamide 600 mg/m(2) (EC) followed by three 28-day cycles of cyclophosphamide, methotrexate and 5-fluorouracil (CMF; n=209). Simultaneous hormonal treatment was applied in both arms. At 5 years' median follow-up, the 5-year event-free survival (EFS) rates were 47.7% (95% confidence interval [CI], 40.2-55.2%) for E120 and 45.9% (38.5-53.3%) for EC-CMF. E120 was as effective as EC-CMF with regard to EFS (hazard ratio [HR] for E120 versus EC-CMF 1.04; 95% CI, 0.79-1.36; p=0.79) and overall survival (HR 1.06; 95% CI 0.77-1.46; p=0.72). The data demonstrate that 4 cycles of dose-intensified epirubicin monotherapy can be as effective as 7 cycles of standard sequential polychemotherapy in high-risk breast cancer patients with > or =10 positive lymph nodes, despite treatment with a single agent and a shorter treatment duration.