The aim of the present study was to evaluate the clinical activity and side effects of a combination chemotherapy consisting of a five-day continuous infusion of fluorouracil and i.v. vinorelbine in metastatic previously treated breast cancer patients. The patient population was represented by 28 women with evaluable disease, previously subjected to chemotherapy, including anthracycline-containing regimens in 89% of patients. Treatment consisted of five-day infusion of 700 mg/m2/day of fluorouracil and vinorelbine, 20 mg/m2 i.v. bolus on day 1 and 6. In the absence of Grade > 3 leukopenia and stomatitis, cycles were repeated every three weeks, for a total of six cycles. Four complete and thirteen partial responses were documented, accounting for a response rate of 61% (95% CI: 40.5-78.5); the clinical efficacy was high even in patients unresponsive to prior anthracycline treatment. The median response duration calculated from the first drug injection was 8 months (range 4-11). Treatment was well tolerated, with 4% Grade 4 stomatitis and 20% Grade 3 leukopenia as the main toxic reactions. This drug combination is active in metastatic previously treated breast cancer patients, is devoid of severe side effects, and warrants further testing.