Purpose: To compare breast cancer prognosis in BRCA1 and BRCA2 mutation carriers with that in patients with sporadic disease. Patients and Methods: An international population-based cohort study was conducted in Canada, the United States, and Australia of 3,220 women with incident breast cancer diagnosed between 1995 and 2000 and observed prospectively. Ninety-three had BRCA1 mutations; 71, BRCA2 mutations; one, both mutations; 1,550, sporadic breast cancer; and 1,505, familial breast cancer (without known BRCA1 or BRCA2 mutation). Distant recurrence and death were analyzed. Results: Mean age at diagnosis was 45.3 years; mean follow-up was 7.9 years. Risks of distant recurrence and death did not differ significantly between BRCA1 mutation carriers and those with sporadic disease in univariable and multivariable analyses. Risk of distant recurrence was higher for BRCA2 mutation carriers compared with those with sporadic disease in univariable analysis (hazard ratio [HR], 1.63; 95% CI, 1.02 to 2.60; P = .04). Risk of death was also higher in BRCA2 carriers in univariable analysis (HR, 1.81; 95% CI, 1.15 to 2.86; P = .01). After adjustment for age, tumor stage and grade, nodal status, hormone receptors, and year of diagnosis, no differences were observed for distant recurrence (HR, 1.00; 95% CI, 0.62 to 1.61; P = 1.00) or death (HR, 1.12; 95% CI, 0.70 to 1.79; P = .64). Conclusion: Outcomes of BRCA1 mutation carriers were similar to those of patients with sporadic breast cancer. Worse outcomes in BRCA2 mutation carriers in univariable analysis seem to reflect the presence of more adverse tumor characteristics in these carriers. Similar outcomes were identified in BRCA2 carriers and those with sporadic disease in multivariable analyses.