The purpose of this investigation was to evaluate the efficacy and toxicity of 6 months' treatment with the combination of epirubicin and docetaxel in metastatic breast cancer. Thirty-eight women (mean age 51 years, range 35-72) with metastatic breast cancer were treated with a regimen of epirubicin 75 mg/m and docetaxel 75 mg/m every 3 weeks, given 4 times if progression was seen upon evaluation after 4 courses or 8 times in responding/stable patients. The patients received 285 cycles of combination treatment and two treatments with docetaxel or epirubicin alone. When neutropenia with fever was observed, further cycles were given with dose reduction. The median cumulative docetaxel dose was 462 mg/m (range 199-600) and that of epirubicin 476 mg/m (range 199-740). The overall response rate was 54% (95% CI 37-71), with a median duration of response of 14.8 months (95% CI 8.8-27.8). Median time to progression was 12 months, median survival 26 months. Neutropenia below 0.5 x 10 /l occurred following 113 (39%) of the total of 285 cycles given; 21 patients (55%) were hospitalized for febrile neutropenia. We conclude that dose tailoring is required in treatment with an epirubicin and docetaxel regimen to avoid grade 3/4 adverse effects in a significant number of patients treated for metastatic breast cancer.