e16520 Background: Venous tumor thrombus (VTT) is observed in 4−10% of newly diagnosed RCC patients, and a successful radical nephrectomy and thrombectomy provides considerable palliation to a proportion of nonmetastatic RCC patients with VTT. However, the reported postsurgical survival varies significantly with the 5‐year overall survival (OS) rate ranging from 37.0 to 71.0%. Hence, accurate risk factors are critically needed for these patients. Here we evaluate the prognostic significance of VTT grading for these patients. Methods: The final evaluable dataset enrolled 706 consecutively nonmetastatic ccRCC patients who underwent radical nephrectomy and thrombectomy, including 304 in the Training cohort from the Eastern China Renal Cancer Collaborative Group, 320 in the China‐Validation cohort and 82 in the Poland‐Validation cohort. All pathological specimens were centrally reviewed by three genitourinary pathologists blinded to clinical information. Univariable and multivariable Cox regression analyses were performed to identify independent predictors associated with survival outcomes. Results: To comprehensively evaluate the potential of VTT in risk assessment, multiple characteristics of VTT were incorporated, including VTT height, consistency and the pathological nuclear grading of VTT (VTT grading), which has not been studied yet. Although higher pathological grading of primary tumor (PT) and VTT were both significantly correlated with dismal prognosis, only VTT grading remained as an independent predictive factor for OS and DFS after multivariable Cox regression. Furthermore, VTT grading showed superiority in risk assessment compared with PT grading and other variables by c‐index analysis (OS: 0.663 vs. 0.501–0.610, 0.667 vs. 0.544–0.651, and 0.719 vs. 0.511–0.700 for Training, China‐Validation, and Poland‐Validation cohorts, respectively; DFS: 0.664 vs. 0.501–0.606, and 0.672 vs. 0.530–0.640 for Training, and China‐Validation cohorts, respectively), which was confirmed by the receiver operating characteristic (ROC) analysis (OS: area under the curve AUC 0.764 vs. 0.650–0.664, 0.684 vs. 0.650–0.667, and 0.814 vs. 0.641–0.711 for Training, China‐Validation, and Poland‐Validation cohorts, respectively; DFS: AUC 0.753 vs. 0.648–0.651, and 0.704 vs. 0.601–0.665 for Training, and China‐Validation cohorts, respectively). Conclusions: VTT grading displayed superior accuracy and discriminatory ability in predicting survival risk for nonmetastatic ccRCC patients with VTT. Assessing VTT grading in routine pathology reports may provide further information for stratification of patient risk.