Background: Recent randomized trials have suggested that high-intermediate risk endometrial cancer patients may safely be treated with adjuvant vaginal brachytherapy (VBT) rather than external beam radiotherapy (EBRT). The purpose of this study was to determine how this paradigm shift might impact clinical outcomes. Methods: All women with stage IA grade 3, stage IA with endocervical gland extension and grade 1-2, or stage IB grade 1-2 endometrioid carcinoma (FIGO 2009 system) treated from 2005 to 2010 at our institution were retrospectively identified. Data was extracted from computerized medical records. Group A consisted of 49 patients in the 1^st half of the study and Group B 40 pts in the 2^nd half. Results: 89 pts underwent abdominal (65%) or minimally invasive (35%) hysterectomy. Group A was more likely to not be surgically staged (28% v 8%; P = 0.02) or have pelvic lymphadenectomy (PLN) only (55% v 33%; P = 0.05). Group B had a much higher rate of both PLN and para-aortic lymphadenectomy (PAALN; 59% v 18%; P < 0.001). Postoperatively, Group A was more likely to receive either EBRT (23% v 0%; P < 0.001) or no radiotherapy (33% v 8%; P = 0.01). Group B more frequently received only VBT (92% v 44%; P < 0.001). 2 of 4 patients with positive/equivocal cytology were the only ones to receive postoperative cytotoxic chemotherapy (6 cycles of paclitaxel and carboplatin). 5 of 89 (6%) patients (3 Group A, 2 Group B) relapsed during the follow-up interval (median 2 years): 2 having positive cytology that did not receive chemotherapy relapsed in the lung and the peritoneum, respectively; 1 staged with PLN only who received postoperative pelvic EBRT relapsed in the para-aortic nodes; 2 relapsed at the vaginal apex, neither of whom had received postoperative radiation. Conclusions: The paradigm shift favoring postoperative VBT cancer is effective at preventing local relapse while avoiding long-term toxicity in women with high-intermediate risk stage I endometrial cancer. Comprehensive PLN and PAALN is integral to this approach by excluding nodal disease. Peritoneal washings, although no longer part of the formal staging system, should be collected and may suggest the need for cytotoxic chemotherapy when positive.