The anthracyclines and taxanes are considered to be the most active drugs in metastatic breast cancer (MBC). We conducted a multicenter phase II study to evaluate the efficacy and tolerability of the docetaxel plus epirubicin combination chemotherapy as first-line treatment in MBC and performed a prospective assessment of the predictive values of circulating HER2 extracellular domain (ECD) and vascular endothelial growth factor (VEGF). Docetaxel 75 mg/m(2) and epirubicin 75 mg/m(2) were given intravenously every 3 weeks. Prophylactic G-CSF was not used. Pretreatment serum HER2 ECD and VEGF levels were measured by enzyme immunoassay. Forty MBC patients were enrolled, and 39 patients were evaluable for toxicities and 38 for response. Complete response was observed in 3 (7.9%) patients, partial response in 20 (52.6%) (overall response rate 60.5%), stable disease in 11 (28.9%) and disease progression in 4 (10.5%). After a median follow-up of 22.5 months, the median duration of response was 28 weeks, median time to disease progression was 32 weeks, and median survival was 15.8 months. Two-hundred and fifteen cycles of treatment were administered (median, 6 cycles per patient). Grade 3 and 4 neutropenia were observed during 24 (11.2%) and 74 (35%) cycles respectively, and grade 3 or 4 febrile neutropenia in 24 (11.2%) cycles. Elevated circulating HER2 ECD levels were found to be associated with a shorter response duration (p<0.005) and shorter time to progression (p<0.005). However, elevated VEGF levels were not found to be correlated with response rate or survival. We concluded that the docetaxel and epirubicin combination is an effective first-line treatment in MBC patients and that elevated serum HER2 ECD levels, but not circulating VEGF levels, predict a poor outcome.