Background: The maintenance hormone therapy (MHT) after cytotoxic chemotherapy is widely used by many clinicians in metastatic breast cancer (MBC) patients with limited evidences. We evaluated the efficacy of MHT and identified those who had benefited the most from it. Methods: MBC patients who had been treated with MHT from 2006 to 2010 in a single institute were retrospectively reviewed. By definition of MHT, the patients should not have progressed during prior chemotherapy. Progression free survival (PFS) was a primary endpoint and predictive factors for PFS were analyzed. Results: 90 patients were reviewed with a median age of 53 (range, 33-70). The median PFS was 13.0 months (range, 1-66). Prolonged PFS was associated with less previous palliative chemotherapy (1 vs 2 vs >2, 16.6 vs 7.4 vs 6.0months, respectively; p=0.006) and less metastatic sites (1 or 2 vs >2, 15.7 vs. 5.5; p=0.03) Multivariate analysis showed that only the number of previous palliative chemotherapy remained as significant variable. (HR 1.59, 95% CI 1.11-2.20; p=0.01) Most patients have not experienced any serious side effects, and only three patients (3.3%) discontinued MHT due to arthralgia, general weakness, and depression. Conclusion: MHT demonstrated considerable efficacy and excellent tolerability in this study. It could be considered as a good therapeutic option in the MBC patients who have not progressed on the cytotoxic chemotherapy. Key Words: Breast cancer, Hormone therapy, maintenance therapy.