Background: There is an underutilization of postoperative radiation therapy (PORT) in renal cell carcinoma (RCC) following radical nephrectomy (RN). The main reason for that is the lack of strong evidence and the contradictory data in the literature regarding its benefit. We aimed to evaluate the efficacy of PORT in locally advanced patients with RCC following complete resection. Materials and Methods: The patients had RN and at least two of the poor prognostic factors like lymph nodes involvement (LN+), renal vein invasion (RVI), inferior vena cava invasion (IVCI) and renal capsule infiltration (RCI) were included in the study. Ninety-four patients were retrospectively evaluated; 56 patient received PORT 50Gy/25 fractions/5 weeks and 38 patients who did not receive PORT were compared. The LN+, RVI, IVCI and RCI were documented in 63 (67%), 46 (49%), 30 (32%) and 71 (76%) patients respectively. Results: Eight patients (14%) in PORT arm developed local recurrence (LR) are compared with 10 patients (26%) for non-PORT arm. Five-year overall survival (OS) rates were 78% and 70% for PORT and non-PORT arms respectively (p = 0.3), while 5-year locoregional control (LRC) rates were 88% for PORT arm and 70% for the non-PORT arm (p = 0.05). The IVCI and LN+ affected OS significantly (p values 0.007 and 0.009) respectively. The RCI and LN+ only affected the LRC with p values 0.03, 0.04 respectively. Two out of 56 patients (3.5%) received PORT developed intestinal obstruction which was treated surgically. Conclusion: The PORT decreased the LR rate in high risk locally advanced RCC patients significantly. The high incidence of distant metastasis offsets this improvement at the level of overall survival.