BACKGROUND: Triple negative breast cancer (TNBC) is associated with different ethnic groups in the United States (US), however this has not previously been examined in a population-based study within the United Kingdom (UK). METHODS: Electronic pathology reports from the North East London Cancer Network (NELCN) on women diagnosed with breast cancer between 2005 and 2007 were collated. The statuses of oestrogen receptor, progesterone receptor and HER-2 were extracted. Women were classified as having TNBC if all three receptor statuses were negative, and as not having TNBC if at least one receptor was positive or borderline. Logistic regression was used to quantify the association between TNBC and ethnicity, adjusting for age, year of diagnosis and socioeconomic deprivation. Overall survival in different ethnic groups was examined using Cox regression, adjusting as appropriate for age, stage of disease, triple negative status, year of diagnosis, socioeconomic deprivation and recorded treatment. RESULTS: There were 2417 women resident in NELCN diagnosed with breast cancer between 2005 and 2007, and TNBC status was determined for 1228 (51%) women. Overall, of women who had their TNBC status determined, 128 (10%) were diagnosed with TNBC. Compared with White women, Black (odds ratio [OR]=2.81, p<0.001) and South Asian (OR=1.80, p=0.044) women with breast cancer were more likely to have TNBC. Black women had a worse age-adjusted survival than White women (hazard ratio [HR]=2.05, p<0.001). This was attenuated by further adjustment for stage of disease (1.52, p=0.032) and triple negative status (1.31, p=0.175). CONCLUSION: Better methods of early detection may need to be developed in addition to more effective systemic treatment in order to improve outcomes for women with TNBC.