We sought to determine if an association exists between age and capecitabine efficacy among patients with metastatic breast cancer (MBC). Pooled analysis of five phase II or III registration trials of capecitabine 2,500-2,510 mg/m(2)/day for 2 weeks and 1 week off, or combination therapy was performed. Four trials enrolled patients previously exposed to other chemotherapy, generally a taxane. Of 570 patients, 193 (34%) were 18-49 years old, 246 (43%) were 50-64, and 131 (23%) were ≥ 65. Median average daily dose was 2,067 mg/m² in the 18- to 49-year-old group and 2,105 mg/m² in the 50-64 and ≥ 65 year groups. Overall survival (OS) in all groups was similar by log-rank test for the individual trials (P = 0.71-0.95) and Cox regression of the pooled trials. Univariate analysis demonstrated no difference in clinical benefit or objective response between groups. Treatment failure analysis showed 283 (50%) patients experienced progressive disease, while 114 (20%) withdrew for safety. Serious adverse events (AEs) occurred in 71 (36.8%), 85 (34.6%), and 59 (45.0%) patients in the 18-49, 50-64, and ≥ 65 years groups, respectively. There was no statistically significant association between age and OS, clinical benefit, or objective response in patients with MBC treated with capecitabine. Frequency of AEs and serious AEs was not related to age at treatment, although women ≥ 65 years were more likely to withdraw from treatment because of an AE than younger women.