Background: The primary treatment for early stage endometrial cancer includes definitive surgical staging procedure followed by adjuvant therapy in women with high risk of recurrence. The optimal interval time between surgery and adjuvant therapy is unclear. Methods: 349,404 patients with primary uterine carcinoma diagnosed from 2004 and 2012 were extracted from National Cancer Database (NCDB). Study population was limited to patients with FIGO 2009 stage I and II endometrial cancer with endometroid, mucinous, clear cell, or serous histology. Adjuvant therapy included radiation therapy, chemotherapy, or a combination. A binary variable of interval time between surgery and adjuvant therapy (“early” vs. “delayed”) was created by using the median time as a cutoff. Analysis of relationship between the interval time and overall survival was performed. Results: Final analysis included 118,373 early stage endometrial cancer patients who had definitive surgical treatment. Median age was 61 (interquartile range 55-69). 87,189 patients (74%) had stage IA disease, 21,573 (18%) patients had stage IB disease, and 9,611 (8%) patients had stage II disease. 28,824 (24%) patients received adjuvant therapy after surgery. The median time from surgery to adjuvant therapy was 1.6 months (interquartile range 1.3-2.2 months). Of the patients that received adjuvant therapy, 48% received intra-vaginal brachytherapy alone, 31% received pelvic external beam radiation, and 7% received a combination of chemotherapy and brachytherapy. There was a significant difference in overall survival in patients who received adjuvant therapy within 1.6 months from surgery and 1.6 months after surgery (Log-rank test, p = 0.04). Patients with advanced age, African-American or Hispanic race, and uninsured status or government-sponsored insurance were associated with delayed treatments. Conclusions: In this large retrospective review of early stage endometrial cancer patients, delayed time between surgery and adjuvant therapy is associated with worse overall survival. Further analysis will be performed to determine an optimal timing between surgery and adjuvant therapy.