We prospectively investigated the efficacy and safety of combining weekly vinorelbine (VNB) with weekly 24-h infusion of high-dose 5-fluorouracil (5-FU) and leucovorin (LV) in the treatment of patients with advanced breast cancer (ABC). Vinorelbine 25 mg m(-2) 30-min intravenous infusion, and high-dose 5-FU 2600 mg m(-2) plus LV 300 mg m(-2) 24-h intravenous infusion (HDFL regimen) were given on days 1 and 8 every 3 weeks. Between June 1999 and April 2003, 40 patients with histologically confirmed recurrent or metastatic breast cancer were enrolled with a median age of 49 years (range: 36-68). A total of 25 patients had recurrent ABC, and 15 patients had primary metastatic diseases. The overall response rate for the intent-to-treat group was 70.0% (95% CI: 54-84%) with eight complete responses and 20 partial responses. All 40 patients were evaluated for survival and toxicities. Among a total of 316 cycles of VNB-HDFL given (average: 7.9: range: 4-14 cycles per patient), the main toxicity was Gr3/4 leucopenia and Gr3/4 neutropenia in 57 (18.0%) and 120 (38.0%) cycles, respectively. Gr1/2 infection and Gr1/2 stomatitis were noted in five (1.6%) and 59 (18.7%) cycles, respectively. None of the patients developed Gr3/4 stomatitis or Gr3/4 infection. Gr2/3 and Gr1 hand-foot syndrome was noted in two (5.0%) and 23 (57.5%) patients, respectively. Gr1 sensory neuropathy developed in three patients. The median time to progression was 8.0 months (range: 3-25.5 months), and the median overall survival was 25.0 months with a follow-up of 5.5 to 45+ months. This VNB-HDFL regimen is a highly active yet well-tolerated first-line treatment for ABC.