5117 Background: Radical nephrectomy (RN) represents the definitive surgical intervention for patients with renal masses suspicious for malignancy and a normal contralateral kidney. However, patients with renal masses are at risk for having or developing chronic kidney disease (CKD) stage III (GFR<60 ml/min/1.73m2) which places them at a higher risk for cardiac morbidity and mortality. We examined if a validated predictive model (SCORED) could help stratify the risk of CKD in patients with renal masses. Methods: We identified 293 consecutive patients who underwent RN for a renal mass without evidence of metastatic disease and with a normal contralateral kidney. Using preoperative risk factors, we stratified patients into low (<4) and high (≥4) SCORED values. Glomerular filtration rates (GFR) were estimated by the MDRD equation. Results: In our cohort, RN was performed for renal masses with an average size of 6.9 cm (range 2–24). A higher SCORED value was associated with a higher risk of patients having CKD stage III prior to surgery (38% vs 18% with a lower SCORED value, p <0.004). Furthermore, among patients with a pre-operative GFR ≥ 60 ml/min/1.73m2, a higher SCORED value was associated with a significantly higher risk for developing CKD stage III postoperatively, at a median follow up of 39.0 months (52% and 65% risk of CKD vs 25% and 32% risk of CKD in patients with lower SCORED value at 12 months, and at 24 months respectively, p=0.010). In multivariate analyses including the size of the mass and pre-operative GFR, the SCORED value was associated with development of CKD. Comparative analyses with another cohort of 171 patients undergoing nephron sparing approaches (NSA) revealed that NSAs significantly protected patients from developing CKD stage III post-operatively. Conclusions: Despite a normal contralateral kidney, patients with high SCORED values are at a significant risk of having or developing CKD following RN for renal masses. Nephron-sparing approaches should be used whenever possible. These findings assume greater importance when considering overall survival outcomes of patients with kidney cancer, as CKD stage III is an independent risk factor for cardiovascular morbidity and mortality. No significant financial relationships to disclose.