Background and Objective: There is marked controversy regarding optimal management patients with stage IB grade III endometrial carcinoma. The present study analyzes the current practices regarding adjuvant radiation therapy for those patients in our institute and also assessed prognostic factor affecting overall survival outcome. Patients and Methods: A total 66 patients with postoperative FIGO stage 1B, grade III endometrial carcinoma were treated and evaluated between the years 2009 and 2014. Risk factors assessed age (4 cm), site of primary tumor (involvement of lower uterine segment versus no involvement), Lymphadenectomy (performed versus not performed), Lymph-vascular space invasion (positive or negative), type of surgery performed (less than total abdominal hysterectomy and bilateral salpingo-ophorectomy (TH/BSO) versus greater than or equal TH/BSO), radiation sequence with surgery (no radiation versus adjuvant radiation), and type of radiation (pelvic external beam radiotherapy versus vaginal brachytherapy versus both). Results: Adjuvant radiation therapy after surgery was associated with significantly better time to relapse (p = 0.001) in comparison to those patients who underwent surgery alone. There was statistically significant improvement of survival of patients who received adjuvant radiation therapy in comparison with those who underwent surgery alone. There was no statistically significant difference in relapse between external pelvic radiotherapy, brachytherapy and both (p = 0.161). There was no statistically significant difference in overall survival between different types of adjuvant radiation therapy (p = 0.318). Adjuvant radiation therapy (HR 0.173, 95% CI 0.049 - 0.609, p = 0.006) and tumor size (HR 4.065, 95% CI 1.120 - 14.761, p = 0.033) were the only statistically significant predictors for relapse in multivariate analysis. Adjuvant radiation therapy (HR 0.159, 95% CI 0.045 - 0.563, p = 0.004), age (HR 10.357, 95% CI 1.195 - 89.746, p = 0.034) and lymphadenectomy (HR 0.240, 95% CI 0.071 - 0.811, p = 0.022) were statistically significant predictors for overall survival. Conclusion: The current study suggested that adjuvant radiation therapy definitely improve survival of patients with stage IB, grade III endometrial cancer. There is a need for more randomized trials to define patients who require adjuvant radiation therapy and define what type of radiation should be received. Well defined guidelines are very important to standardize treatment and cut costs in clinical practice.