INTRODUCTION: With the advent of genomic assays, sentinel lymph node biopsy (SLNB) may be less impactful in determining adjuvant breast cancer therapy. We evaluated the influence of SLNB on adjuvant therapy recommendation when the Oncotype DX recurrence score (RS) is known. METHODS: We reviewed postmenopausal women with ER-positive/HER2-negative, pT1-2 breast cancers with non-suspicious axillary ultrasound treated with SLNB at the time of cancer resection, from 2011 to 2015. For each case, the recommended adjuvant therapy based on the actual SLNB was compared with recommendations if SLNB had been omitted (presumed negative). RESULTS: Surgical nodal status was N0 in 184 patients (84.8%), Nmi-N1 in 29 patients (13.4%), and N2-3 in 4 patients (1.8%). SLNB resulted in a recommendation for axillary lymph node dissection in 4.1% (n = 9). Axillary surgery resulted in a change in radiation recommendation (nodal radiation considered or recommended) in 15.2% (n = 33). Of the 147 patients with known RS, 95 patients had RS > 18, 29 had RS 18-25, and 23 had RS < 25. When chemotherapy was only recommended for RS > 25, or N2-3 disease, SLNB changed the recommendation to have chemotherapy in one patient (0.7%), and the recommendation of which chemotherapy regimen (second- vs. third-generation) in an additional 5 patients. CONCLUSION: SLNB changed the recommendation for/against chemotherapy, or the chemotherapy regiment recommended, in 4.8% of postmenopausal women with early-stage, ER-positive/HER2-negative breast cancer, and sonographically negative axilla when using RS > 25 or N2-3 disease as an indication for chemotherapy. Preoperative genomic profiling can guide de-escalation of axillary surgery.