Background: Triple-negative breast cancer (TNBC) is associated with a high recurrence rate and poor prognosis, despite high initial response to chemotherapy. It is not known if TNBC patients 75 years older, an age group less likely to be treated with adjuvant chemotherapy, have the same mortality risk as younger women. Methods: We conducted a prospective cohort study of all women presenting with primary TNBC, age 21-89, stage I-III from 1998-2009 identified and tracked by our registry (n=529). Clinical characteristics were chart abstracted at diagnosis and follow up. The Kaplan-Meier method and log rank test were used for disease specific survival (DSS) and overall survival (OS) by age. Results: Mean follow up was 6.6 years, range 1.98-13.41 years. Distribution by age was 92% <75 years (n = 485) and 8% 75+ years (n = 44). The two age groups did not differ by histologic or nuclear grade, stage, or radiation therapy receipt (age 75+ by stage: I = 46%, II = 34%, III 21%, age <75: I = 37%, II = 46%, III = 17% [not significant]). Patients 75 and older were less likely to be treated with adjuvant chemotherapy (32% vs. 91%, Pearson chi square test = 119.32, p <.001). 5 year DSS was not significantly different for patients age <75 years compared to patients age 75+ years (85% vs. 84%). However, 5 year OS was significantly worse for 75 year and older patients (65%) compared to <75 year old patients (83%) (log rank test = 13.97, p < .001). Conclusions: In our institutional cohort, triple-negative breast cancer in older women had similar prognostic indicators (stage and histologic grade) compared to younger women and older women had equivalent disease specific survival in spite of substantially less chemotherapy treatment. At 5 years post diagnosis, women 75 years and older were 18% more likely to die of causes other than breast cancer.