OBJECTIVE: To evaluate trends and factors predicting use of renal mass biopsy (RMB) for localized Renal Cell Carcinoma in the United States (US) in the context of current guidelines recommendations. METHODS: We queried the National Cancer Database for cT1-cT3N0M0 Renal Cell Carcinoma diagnosed between 2004 and 2015. Temporal trends of RMB were characterized based on tumor size, treatment (partial nephrectomy [PN], radical nephrectomy [RN], ablation, and no treatment), age and Charlson Comorbidity Index with slopes compared using analysis of variance. Multivariable analysis was used to determine factors associated with use of RMB. RESULTS: Of 338,252 patients analyzed, 11.9% (40,276) underwent RMB. Use of RMB increased throughout the study period from 1,586 (7.6%) in 2004 to 5,629 (16.2%) in 2015 (P < 0.001). Use of RMB increased greatest for ablation (27 to 63%, P < 0.001) and tumors 2-4 cm (9 to 20%, P < 0.001). Multivariable analysis showed year of diagnosis (OR = 1.06; P < 0.001), higher education (OR = 1.09; P < 0.001) and insured status (OR = 1.23; P < 0.001) were associated with increased RMB. Compared to tumors ≤2 cm, tumors 2.1-4 cm (OR = 1.36; P=<0.001), 4.1-7 cm (OR = 1.18; P <0.001) and >7 cm (OR = 1.05; P = 0.03) were associated with higher rates of RMB. Compared to RN, PN was not associated with increased RMB (OR = 1.00; P = 0.92), while ablation (OR = 10.90; P < 0.001) and no surgical treatment (OR = 4.83; P < 0.001) were. CONCLUSION: RMB utilization increased overall, with largest increase associated with ablation. Nonetheless, only two-thirds of patients underwent RMB with ablation, suggesting persistent underutilization. Rates of RMB for tumors ≤2 cm and in those undergoing no treatment increased less, suggesting less utilization for surveillance. However, rates for tumors >2-4 cm increased more, suggesting selective utilization of RMB to guide decision-making and risk stratification in small renal masses.