Purpose: To evaluate the association between angiotensin receptor blocker (ARB) usage and breast cancer characteristics and outcomes. Methods: All patients who were treated in our institute for estrogen receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer between April 2005 and March 2012 and whose tumors were sent for Oncotype-DX analysis were included. Medical records were retrospectively reviewed. Data regarding ARB usage were retrieved. Usage of several prespecified medications for hypertension was also evaluated. Each medication group was compared with the rest of the cohort. Results: A total of 671 patients were included. Forty-six (7%) patients were treated with ARB. ARB usage was associated with macroscopic nodal involvement (p < 0.001) and a more advanced stage at diagnosis (p < 0.001). These findings remained significant in the multivariate analysis. Patients treated with ARB also had a higher incidence of invasive lobular carcinoma subtype (p = 0.009), a worse 5-year breast cancer-specific survival (94.7 vs. 98.8%, p = 0.024) and a worse 5-year overall survival (94.6 vs. 98.8%, p = 0.015), but these differences were not demonstrated in the multivariate analysis. Conclusions: Patients treated with ARB presented with a more advanced breast cancer disease and some distinct histological features. Further research is required to elucidate the effect of ARB treatment on breast cancer.