This report summarizes the clinical experience of investigators at the istituto Nazionale Tumori in Milan, Italy, with intravenous paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) infused over 3 hours plus bolus doxorubicin in women with untreated breast cancer. The overall experience indicates that the combination of paclitaxel/doxorubicin is a very active primary chemotherapy for stage IV breast carcinoma and is associated with manageable toxicity. The results suggest that the incidence of cardiotoxicity and duration of neutropenia can be reduced by limiting the total cumulative dose of doxorubicin to 360 mg/m2 and by adding granulocyte colony-stimulating factor to the primary chemotherapeutic regimen. In addition, the study indicates that continuous treatment of responding patients with single-agent paclitaxel after this combination increases the patients' chances of complete response. These favorable results indicate that this regimen could be a very effective treatment option as adjuvant or neoadjuvant chemotherapy in women with early stage operable breast cancer as well as those with advanced breast cancer.