A pilot study of primary chemotherapy with bolus doxorubicin plus paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) infused over 3 hours was performed in 38 women with locally advanced and 41 with stage II/III breast cancer. Patients received four cycles of primary chemotherapy followed by surgery and treatment with cyclophosphamide/methotrexate/5-fluorouracil for six cycles. Preliminary data are available on 73 patients. Doxorubicin plus paclitaxel was well tolerated. Primary toxicity consisted of grade 1 or 2 reversible peripheral neuropathy and grade 3 alopecia. After a median follow-up of 13 months, none of the patients have developed cardiac toxicity or any significant alteration of the left ventricular ejection fraction, which was measured before treatment, at each cycle of doxorubicin plus paclitaxel, and every 3 months thereafter. Major clinical response of the breast tumor was observed in 88% of patients. At pathologic examination of the surgical specimen, 40% were pT1, 15% had no macroscopic tumor residue, and 7% had complete disappearance of invasive neoplastic cells. After a median follow-up of 17 months for patients with locally advanced breast cancer, freedom from progression was 67%, disease-free survival was 71%, and overall survival was 74%. The same end points were 100% for patients with stage II/III disease, with a shorter median follow-up of 10 months. In conclusion, doxorubicin plus paclitaxel is safe, feasible, and effective, and can be used as primary or adjuvant chemotherapy to assess its actual therapeutic role in women with early breast cancer.