We treated 12 patients with metastatic breast cancer with weekly paclitaxel therapy. Paclitaxel was administrated by 1 hour infusion at a dose of 80 mg/m2 after short premedication every week on an outpatient basis. Administration was continued for 3 weeks followed by 1 week rest. All patients had received prior metastatic chemotherapy, and prior anthracycline therapy was done in 66.7% of the patients. Partial responses were observed in 66.7% of the patients and progressive disease in 33.3%. The response rate was 66.7%. Responses were observed in 62.5% of the patients with prior anthracycline therapy. Grade 3/4 leukopenia and neutropenia occurred in 25% of the patients, respectively, and no grade 3/4 peripheral neuropathy was observed. Dyspnea occurred in 25% of the patients and was grade 3 in 16.7%. Dyspnea is thought to be one of the adverse events requiring caution with weekly paclitaxel administration. Weekly paclitaxel therapy is effective and well tolerated in patients with metastatic breast cancer.