Background: The Canadian health care system was designed to provide equitable access to equivalent standards of care. We aim to examine if BC pts with different SES received different care and had different overall survival (OS) in Ontario, Canada’s largest province. Methods: Female pts diagnosed with BC between 2003-2009 were identified from the Ontario Cancer Registry and linked to databases related to physician claims, hospital and emergency visits and provincial funding programs to ascertain demographics, cancer stage (CS), comorbidities, mammography use, surgery type, adjuvant chemotherapy (chemo), radiation (RT), and vital statistics. SES was defined as neighbourhood income by postal code attained from Statistics Canada and divided into income quintiles (Q1-Q5; Q5=highest). Univariate and multivariable analyses were used to examine the association between i) SES and mammogram screening and BC treatments, and ii) SES and OS. Results: 34,446 BC pts with CS available were identified. 76.0% were > 50 years old. The proportion of CS I, II, III and IV were, 41.4, 38.8, 14.9, & 4.9%, respectively. Screening mammograms (1-5 years prior to diagnosis) rates were significantly higher with higher SES (Q5 = 50.1% and Q1=41.7% (OR = 1.43, 95% CI: 1.32-1.56, p<0.0001)) for pts age >55. Pts with higher SES were more likely to be diagnosed at an earlier CS (p<0.0001, Q5=44.3% & Q1=37.7% were diagnosed with CS (OR = 1.31, 1.23-1.41)). Pts with higher SES were more likely to receive adjuvant chemo (p<0.0001, Q5 vs. Q1 OR = 1.18, 1.10-1.26) and RT (p<0.0001, Q5 vs. Q1 OR = 1.24, 1.15-1.33). There were no obvious differences in adjuvant trastuzumab (T-mab) use (p=0.62), breast conserving surgery (p=0.057) and time between surgery and adjuvant chemo (p=0.15) based on SES. The 5 year OS rates for Q1-Q5 were 80.0, 81.0, 82.2, 83.9 & 85.7%, respectively (p<0.0001). After adjusting for age, CS, comorbidities, rural residence, use of adjuvant chemo, T-mab, RT and surgery type, higher SES remained associated with better OS (p=0.0017). Conclusions: Higher SES is associated with more use of screening and treatments, and better OS in BC pts in a universal health care system.