Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) is active against advanced breast cancer and anthracycline-resistant breast cancer. We assessed the efficacy and toxicity of doxorubicin followed by a 3-hour infusion of paclitaxel in women with advanced breast cancer. Participants could have received at most one prior adjuvant chemotherapy regimen, but no previous exposure to anthracyclines or taxanes was permitted. The patients were treated every 3 weeks with doxorubicin (50 or 60 mg/m2) followed 30 minutes later by paclitaxel (155, 175, or 200 mg/m2). After reaching the maximum cumulative doxorubicin dose, treatment could be continued with paclitaxel alone. Thirty women were included, of whom 29 were evaluable for response. The overall response rate was 83% (95% confidence interval, 64% to 94%), with 24% of patients attaining complete remission. Median response duration for complete responders was 8+ months (range, 4 to 13 months) and median time to progression was 9 months (range, 2 to 18 months). Main toxicities were neutropenia, paresthesia, nausea/vomiting, alopecia, myalgia, and cardiotoxicity. In 15 patients (50%), the left ventricular ejection fraction decreased to below normal levels; six patients (20%) developed congestive heart failure. In conclusion, the combination of doxorubicin and paclitaxel is highly active; dose-limiting toxicities are neutropenia, neuropathy, and cumulative cardiotoxicity.