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PURPOSE While surgical approach has recently been associated with positive surgical margin (PSM) after partial nephrectomy (PN) for small (<4 cm) renal masses, its impact on margin status for large (>4 cm) masses is unclear. We sought to evaluate the relationship between margin and surgical approach in patients undergoing PN for large renal masses. MATERIALS AND METHODS Using the National Cancer Database (NCDB), we identified patients undergoing PN for pathological T1b and T2a renal-cell carcinoma diagnosed from 2010 to 2013. Conversions to open surgery were also included in our analysis. The primary outcome was surgical margin status. Multivariable regression modeling was performed to identify factors associated with PSM. A propensity score matching analysis was then performed to evaluate the impact of margin status on overall survival (OS). RESULTS Of the 7495 patients undergoing PN for pT1b and pT2a renal masses over the study period, 504 (6.7%) had PSM. On multivariable analysis, surgical approach (laparoscopic or robot assisted vs open) was not significantly associated with surgical margin (p = 0.12 and p = 0.44, respectively). Tumor stage (T2a vs T1b) also showed no significant association (p = 0.18). A subsequent multivariable analysis using clinical staging showed that surgical approach (p = 0.28 and p = 0.54, respectively), tumor stage (p = 0.78), and conversion-to-open surgery (p = 0.98) had no significant association with PSM. Propensity score matched analysis showed that PSM was not significantly associated with OS (hazard ratio 0.95 [95% confidence interval 0.47-1.92] p = 0.88). CONCLUSION In a contemporary nation-wide cohort, surgical approach was not associated with an increased risk of PSM for large, noninvasive renal masses. Furthermore, increased size from T1b to T2a was not associated with an increased risk of PSM. These data suggest that surgical approach should be selected by surgeon comfort level with an individual tumor, rather than the size of the tumor itself.