OBJECTIVES: Few studies have examined racial disparities in invasive breast cancer among women aged 18-44 years in the United States. This study estimates the magnitude of racial disparities in breast cancer among younger women using five measures of population health: life expectancy (LE), expected years of life lost (EYLL), cumulative incidence rate (CIR), and incidence and mortality rate ratios (IRR and MRR). METHODS: The LE and EYLL were estimated for black and white women from a Surveillance, Epidemiology, and End Results cohort of 37,857 women ages 18-44 years diagnosed with invasive breast cancer, 2000-2011. The survival function for an age- and sex-matched reference population was generated using the Monte Carlo method from the life table of the general population. Lifetime survival of the breast cancer patients (up to 60 years) were obtained using linear extrapolation of a logit-transformed curve of the survival ratio. The CIR, IRR and MRR were calculated using 2007-2011 breast cancer incidence and mortality rates from the Centers for Disease Control and Prevention’s National Program of Cancer Registries. RESULTS: The estimated LE for younger black women ranged from 29.8 for localized stage to 5.3 years for distant stage, and 33.1 to 8.7 years for white women. The estimated EYLL was 17.1 years for black and 13.6 years for white women. The CIRindicated a 1 in 85 probability for black women compared to a 1 in 92 probability for white women of being diagnosed with breast cancer by age 45. The estimated age-adjusted breast cancer IRR for black-to-white women was 1.06 and the corresponding MRR was 1.88. CONCLUSIONS: The persistent breast cancer disparities between younger black compared to white women highlight the need for continued public health efforts to understand etiology, promote primary prevention, and improve access to quality healthcare.