Objective: The purpose of this study was to evaluate the efficacy and feasibility of the R.E.N.A.L. Nephrometry Score to postoperatively predict high-grade clear-cell renal carcinoma (ccRCC). Methods: The study included 288 patients diagnosed with ccRCC who had complete CT/CTA data and R.E.N.A.L. Nephrometry Scores and underwent renal surgery at our center between January 2012 and December 2015. The relationship between the pathological grade of renal masses and R.E.N.A.L. Nephrometry Score was evaluated. Results: Univariate analysis indicated that diagnostic modality, cystic necrosis, enlargement of the regional lymph node, distant metastasis, clinical T stage, TNM stage, surgical modality, tumor size, nearness of the tumor to the collecting system or sinus, total Nephrometry Score and individual anatomic descriptor components were significantly associated with postoperative tumor grade (P < 0.05). Multivariate analysis showed that tumor size, the maximal diameter (R score), exophytic/endophytic properties (E score) and the location relative to the polar lines (L score) were independent prognostic factors to preoperatively predicting ccRCC pathological grade. The areas under the ROC curve with respect to the multi-parameter regression model (0.935, 95%CI: 0.904-0.966), tumor size (0.901, 95%CI: 0.866-0.937), R score (0.868, 95%CI: 0.825-0.911), E score (0.511, 95%CI: 0.442-0.581) and L score (0.842, 95%CI: 0.791-0.892) were calculated and compared. Conclusion: Tumor size, as well as R, E, and L scores were independent prognostic factors for high-grade pathology. Lager tumor sizes and higher R, E and L scores were more likely to be associated with high-grade pathological outcomes. Thus, the R.E.N.A.L. Score is of practical significance in facilitating urologists to make therapeutic decisions.