OBJECTIVES: Older women with breast cancer are less likely than younger women to receive guideline-concordant care (GCC) according to evidence-based treatment guidelines put forth by the National Comprehensive Cancer Network. This study compared survival outcomes between older women with stage I – III breast cancer by receipt of GCC (yes vs. no). METHODS: The linked SEER-Medicare data set was used to identify of 27,883 women, age > 66, diagnosed in 2004 to 2009 with pathologically staged I, II, and III breast cancer. Algorithms considering clinical cancer characteristics and the appropriate course of care as per guidelines vs. the actual care received, were used to determine receipt of GCC (yes vs. no). Five-year survival rates, adjusted hazard ratios, and Kaplan-Meier survival curves were estimated, adjusting for study covariates. RESULTS: The average time-to-death was 1,246.7 days (SD = + 600.8) with an 88% 5-year survival rate. Women receiving GCC had higher survival rates than those who did not (93% vs. 85%) (p< .0001). Groups of women with the greatest risk of death within 5 years of diagnosis were those age > 80 years (AHR, 2.85; 95% CI, 2.54, 3.20), a comorbidity score > 2 (AHR, 2.09; 95% CI, 1.92, 2.27), diagnosed at stage III (AHR, 1.81; 95% CI, 1.48, 2.21), did not receive GCC (AHR, 1.18; 95% CI, 1.04, 1.35), and did not receive RT (AHR, 1.53; 95% CI, 1.39, 1.68). CONCLUSIONS: Older women who received GCC for breast cancer had greater overall survival, than those who did not receive GCC. Considering that many older women may not receive the aggressive standard of care due to declining health and vitality, overall breast cancer survival could be improved by targeting modifiable risk factors such as earlier stage at diagnosis and decreased comorbidity by way of promoting persistent routine mammography screening and healthy lifestyle behaviors.