Seven patients with inflammatory and 11 with metastatic breast cancer were treated with high dose FEC chemotherapy plus GM-CSF; 5-fluorouracil and cyclophosphamide were administered at 500 mg/m2/iv/day 1, epirubicin at three dose levels: 100 mg, 120 mg and 140 mg/m2/iv/day 1 every three weeks (six patients per level). GM-CSF was administered at a dosage of 5 mg/kg/sc from day 5 to 12 of each cycle. The overall response rate was 83% (95% CI: 66%-100%) with 22% complete response. The median response duration for patients with metastatic disease was 7 months (range: 4-10). The hematological toxicity was moderate but reversible due to GM-CSF rescue; mucositis represented the dose limiting toxicity. In conclusion, the increase of dose intensity resulted in a higher response rate but not longer response duration, which must be taken into account when administering high-dose chemotherapy with growth factor rescue.