To evaluate the efficacy and toxicity of high-dose epirubicin (EPI) plus cyclophosphamide (CPA) therapy, a phase II study of EPI, 130 mg/m2, plus CPA, 1000 mg/m2, with G-CSF every 3 weeks was carried out for 51 advanced or recurrent breast cancer patients by the Japan Clinical Oncology Group (JCOG). Fifty out of the 51 patients who were eligible for our criteria were treated with this regimen as first-line chemotherapy for visceral metastases or hormone-independent tumors. In this trial, 203 cycles were administered with an average of four cycles per patients. In 50 patients who were evaluable for response, there were 7 complete (CR) and 25 partial responses (PR) with an overall response rate of 64% (95% confidence interval, 50.1-75.9%). Symptomatic and hematological acute toxicity more than grade 3 occurred frequently; however, no treatment-related death occurred. The incidence of toxicities (> or = grade 3) was as follows: leukopenia 98%, thrombocytopenia 42%, nausea/vomiting 56% and hair loss 12%. In each cycle, daily administration of 2 micrograms/kg G-CSF (granulocyte-colony stimulating factor) was given on days 2-15 subcutaneously. The incidence of cardiotoxicity was low. Arrhythmia (< or = grade 2) was observed in 8% and a slight decrease of ejection fraction index (< or = grade 2) was observed in 2% in this trial. The median follow-up period for patients was 37.2 (24.6-51.5) months and the median survival period was 17.4 months. These data indicate that high-dose EPI + CPA combination chemotherapy was effective and well tolerated for breast cancer patients with visceral metastases or hormone-independent tumors. A randomized trial of high-dose EPI vs conventional chemotherapy is required to ascertain the usefulness of this regimen.