摘要Objective: It remains unclear whether simultaneous use of two chemotherapeutic drugs is better than sequential use. This trial was designed to explore efficacy and safety of sequential vs simultaneous use of vinorelbine and capecitabine at the same dosage as first-line therapy in metastatic breast cancer (MBC). Methods: This was a un-icenter, randomized phase Ⅱ trial. Patients randomized into the simultaneous group (group A) were simultaneously administered with vinorelbine and capecitabine while those in the sequential group (group B) received vinorelbine followed by capecitabine at the same dosage. Results: Sixty-six patients were screened and 30 patients were randomized into either group. There're significant differences in the clinical benefit rate (CBR) with 80.0% for group A vs 53.3% for group B (P = 0.028). With a median follow up time of 13.5 months, there were no significant differences between the two groups in PFS (median PFS: 7.70 months for group A vs 7.23 months for group B, P = 0.436). Grade Ⅲ or Ⅳ neutropenia (83.3% vs 50.0%, P = 0.006), all grades of fatigue (56.7% vs 30.0%, P = 0.037) and anorexia (53.3% vs 23.3%, P = 0.017) were significantly more frequent in simultaneous group. Conclusion: Simultaneous administration of vinorelbine and capecitabine can bring about improvements in CBR, but cannot translate into long-term benefits, such as progression-free survival (PFS) or overall survival (OS). These findings,combined with a relatively better tolerability in sequential group, showed that both simultaneous and sequential administrations are reasonable options for MBC patients.