In order to shed light on genetic and environmental factors contributing to breast cancer health disparities, anonymous data from the cancer registry in Brooklyn, NY and two countries in the Caribbean, have been analyzed and compared. De-identified data were obtained on 3,710 women from three cancer registries in Brooklyn (New York), Guyana, and Trinidad, all having been diagnosed with breast cancer between 1995 and 2007, with follow-up through to early 2009. There was a significant difference in breast cancer survival according to race, place of birth, and place of residence. Women of African origin had a significantly worse survival than White women. Women born in the Caribbean had significantly worse survival in comparison to their counterpart born in the US, independently from their ethnic background (adjusted hazard ratio: 1.6; 95% CI: 1.2-2.1). A significant lower breast cancer survival was observed in African Caribbean women living in the Caribbean (HR: 1.8; 95% CI: 1.6-2.1) versus African-Caribbean women born in the Caribbean and living in the US (HR: 1.3; 95% CI 1.1-1.7), versus African-descent women born and living in the US. This study suggests that biological, behavioral, environmental, and clinical factors play a significant role in the observed difference in breast cancer outcome in women of Afro Caribbean descent.