The efficacy of combination therapy with vinorelbine, cyclophosphamide, and 5-fluorouracil was assessed in women who had received no prior therapy for locally advanced or metastatic breast cancer. Sixty patients with metastatic breast cancer who had finished any adjuvant therapy at least 6 months previously and who had not received treatment for advanced disease were entered onto the study. The schedule consisted of vinorelbine (Navelbine, Pierre Fabre Medicament) 25 mg/m2 on days 1 and 8, cyclophosphamide 500 mg/m2 on day 1, and 5-fluorouracil 500 mg/m2 followed by folinic acid 200 mg/m2 on days 1 and 8. Treatment was repeated every 21 days up to a maximum of 8 cycles. Objective responses were observed in 27 of 60 patients (45%; CI95 32.4-57.6) including 4 complete responses (6.7%; CI95 0-13) and 23 partial responses (38.3%; CI95 22.5-54.1). The responses were achieved in both visceral and nonvisceral sites and at the same rate for patients with multiple sites of disease. Neutropenia was dose limiting, with 40% of patients affected at grade 3 or 4, while other hematologic and nonhematologic toxicity was very mild. This schedule achieves good levels of response without the use of an anthracycline, so it is suitable either for patients who have been extensively exposed to anthracyclines during adjuvant therapy or for those who have other contraindications to their use.