This phase II study was designed to evaluate the response rate (RR) and toxicity of gemcitabine/vinorelbine in patients with metastatic breast cancer. All patients had previously received anthracyclines. Treatment consisted of gemcitabine 1200 mg/m2 and vinorelbine 30 mg/m2 on days 1 and 8, every 3 weeks. Twenty-five patients were enrolled. Median age was 59 years (range, 33-73 years). Ten patients had received only adjuvant therapy with anthracyclines. The remaining 15 patients had received chemotherapy for metastatic disease, including taxanes in 11 cases. Four patients could not be evaluated for response. By intent-to-treat analysis, the overall RR was 44% (95% CI, 24.4%-65%). Median duration of response and median time to treatment failure were 21 and 17 weeks, respectively. The main toxicity was hematologic, with grade 3/4 neutropenia occurring in 13 patients and 1 patient developing febrile neutropenia. Two deaths from pneumonia occurred. These results reveal an encouraging activity with a reasonable toxicity profile in a patient population with an unfavorable prognosis. Our group is conducting a randomized study to compare this combination with vinorelbine alone in patients with metastatic breast cancer after failure to respond to anthracyclines and taxanes