This report evaluates the activity of paclitaxel alone (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), carboplatin alone, and their combination in the treatment of patients with advanced breast cancer. The preliminary safety information of this combination in other tumor types also is discussed. Finally, the overall rationale for ongoing study of the efficacy of paclitaxel and carboplatin, along with appropriate translational studies, as first-line chemotherapy in patients with metastatic breast cancer is examined. Both paclitaxel and carboplatin have well-established single-agent activity in the treatment of women with breast cancer. The tolerability of this combination, using the sequence paclitaxel followed by carboplatin infusion, already has been established in patients with lung cancer and ovarian cancer. In addition, this therapy has the novel attribute of a relative platelet-sparing effect. A phase II trial evaluating the efficacy of the paclitaxel/carboplatin combination, along with an evaluation of thrombopoietin levels and quality of life, has been initiated recently through the North Central Cancer Treatment Group. In this trial, intravenous paclitaxel 200 mg/m2 infused over 3 hours is followed by carboplatin at a calculated area under the concentration-time curve dose of 6, with cycles repeated every 21 days. Results from this trial will help document the role of the paclitaxel/carboplatin combination in the treatment of women with breast cancer.