Background: Adjuvant bisphosphonates in early breast cancer (BC) have resulted in reduction in bone metastasis and improved overall survival (OS), particularly in post-menopausal women. We aim to evaluate the effect of bone-modifying agents (BMA) on survival in a population based cohort of older BC patients. Methods: Patients aged ≥ 66 yo diagnosed with stage I-III BC between 2007 and 2013 were identified in SEER-Medicare and TCR-Medicare database. Patients were required to have Medicare Parts A, B and D coverage. Patients receiving at least 6 months of an oral bisphosphonate, two doses of ibandronate or one dose of zoledronate or denosumab at doses equivalent or higher to those approved for osteoporosis, during the first two years of BC diagnosis were identified as having received a BMA. Five year-OS was estimated with Kaplan-Meier with groups compared with the log rank test. Cox proportional hazards models were fitted to determine the association of BMA and OS after propensity score adjustment. Subgroup analysis were stratified by stage. Results: The final cohort included 37,604 patients. Median age was 75 years. 32,045 (85.2%) of the patients had hormone receptor-positive tumors. Overall, 8,591 (22.8%) of the patients were treated with BMA. Of these, 7,349 (85.5%) received bisphosphonates only. The unadjusted 5 year OS was 81% and 77 % for those who did and did not receive BMA, respectively (P < 0.0001). After multivariate analysis including propensity scores adjustment, treatment with BMA was associated with a statistically significant increased survival (Hazard ratio [HR] 0.91, 95% CI = 0.85-0.96). When stratified by stage, BMA vs no BMA showed an improvement in unadjusted 5 year OS in patients with Stage II (5y OS 79% vs 72%, P < 0.0001) and Stage III (64% vs 57%, P = 0.002) but not for Stage I (86% vs 85%, P = 0.88). After multivariate adjustment, survival remained significant for Stage II (HR 0.81, 95% CI = 0.73-0.90) but not for Stage III (HR 0.91, 95% CI = 0.78-1.07). Conclusions: Use of BMA in post-menopausal woman with early stage BC patients was associated with improved 5 year OS. Stage stratified subgroup analysis showed that the difference in survival was significant only for patients with stage II.