Anthracyclines are the gold standard monotherapy for metastatic breast cancer. Higher response rates are seen with drug combinations, especially with newer agents such as taxanes. The purpose of this study was to evaluate the toxicity and activity of the combination of paclitaxel and epirubicin in patients with advanced breast cancer. Thirty-five women with locally advanced or metastatic breast cancer (first and second relapse) were treated with epirubicin 75 mg/m2 and paclitaxel 200 mg/m2 3-weekly. Six centres recruited 35 patients; 34 (97%) were assessable for response. Eighteen had undergone prior chemotherapy, including six (17%) with anthracycline-containing regimens. Grade 4 neutropenia was found in 33 patients (94%), which was of 4 days' average duration; however, infective complications were rare, with only nine cycles (6%) complicated by neutropenic sepsis. There were two sepsis-related deaths. Symptomatic cardiotoxicity was infrequent, although a >15% decline in cardiac function was recorded in five patients (14%). Grade 3 peripheral neuropathy occurred in three patients (9%). The overall response rate was 50% (95% confidence interval 33-67) (complete response 12%; partial response 38%), with a median duration of response of 31 weeks. The median time to progression was 27 weeks, with a median survival of 48 weeks. This regimen appears to be a relatively safe, tolerable and effective treatment for advanced breast cancer. A United Kingdom Co-ordinating Committee for Cancer Research Phase III trial (AB-01) comparing this combination of epirubicin and paclitaxel with cyclophosphamide and paclitaxel completed accrual in November 1999.