Background: Health insurance can influence utilization of cancer care. We sought to determine whether insurance status impacts treatment patterns and survival in women with stage 0-IV breast cancer. Methods: Women ages 18-69 years old, diagnosed with unilateral stage 0-IV breast cancer between 2004 and 2014 were selected from the National Cancer Data Base. Insurance status was categorized as Private, Medicare (65+ yo), Medicare (18-64 yo), Medicaid, or Uninsured. After adjustment for known covariates, generalized and binary logistic regression were used to estimate the association of insurance type with receipt of treatment. A multivariate Cox proportional hazards model was used to estimate the association of insurance status with overall survival. Results: A total of 610,450 women met inclusion criteria. Median age was 56 (48-63). Insurance status included: 72.1% Privately insured, 13.9% Medicare 65+, 4.8% Medicare 18-64, 7.1% Medicaid, and 2.1% Uninsured. Women with private insurance were more likely to present with stage 1 breast cancer, and less likely to present with stage 4 disease when compared to Medicaid or Uninsured patients (stage 1: 63.4%, 49.4%, 48.2%, p < 0.01; stage IV: 0.8%, 1.8%, 2.1%, p < 0.01). Risk of death was higher in uninsured or Medicaid patients when compared to those with private insurance (HR 1.52, 95% CI 1.41-1.64; HR 1.6, 95% CI 1.52-1.68). Receipt of chemotherapy and radiation did not differ between Medicaid, Uninsured, or Privately insured patients, but women without private insurance were more likely to receive neoadjuvant chemotherapy (OR 1.14, 95% CI 1.09-1.19; OR 1.16, 95% CI 1.07-1.25, respectively, p < 0.01). Uninsured women were more likely to undergo mastectomy without reconstruction (OR 1.57, 95% CI 1.49-1.65), and less likely to undergo unilateral or bilateral mastectomy with reconstruction than lumpectomy and radiation (OR 0.57, 95% CI 0.53-0.61; OR 0.35, 95% CI 0.32-0.39). Conclusions: Stage at diagnosis and risk of death were higher in Medicaid and uninsured breast cancer patients when compared to those with private insurance. Insurance status did not predict differences in receipt of surgery, chemotherapy, or radiation but did affect oncologic outcomes.