Background: The impact of surgical resection of renal tumors on peripheral immune related cells is not well characterized, and has potential implications as biomarkers for systemic immune therapy are being developed. We sought to assess the effect of surgical resection on circulating cytotoxic T-cells (CTLs) for patients with renal tumors. Methods: We prospectively enrolled 40 patients undergoing partial, radical, or cytoreductive nephrectomy (PN, RN, CN) for unilateral primary renal tumors between 2016 and 2018. Blood draws were performed pre-op, 1 day post-op, and 3 months post-op. Flow cytometry was performed on peripheral blood mononuclear cells (PBMCs). The % of PBMCs expressing CD11a/CD8 (CTLs) were assessed. The % of CTLs expressing PD-1, Bim (a downstream PD-1 pathway pro-apoptotic mediator), CX3CR1/GZMB (an effector memory T-cell phenotype), and Ki67 (a proliferation marker) were assessed. Median changes in % of CTLs were evaluated with the Wilcoxon signed rank test. Comparisons between aggressive (pT3-4, N1, M1, or aggressive histology (high-grade, coagulative necrosis, sarcomatoid dedifferentiation, or specific RCC-variant histologies)) versus indolent tumors were assessed using the Wilcoxon rank sum test. Results: Twenty, 12, and 8 patients underwent RN, PN, and CN, respectively. Thirty, 7, and 3 patients had clear-cell RCC, non-clear cell RCC, and oncocytoma, respectively. Twenty-three and 17 patients had aggressive and indolent tumors, respectively. While there was no significant change at 1 day, by 3 months there were significantly increased CTLs among PBMCs (+1.3%; p=0.004). There was significant decrease in CX3CR1+GZMB+ CTLs (-2.9%; p<0.001) and significant increase in Bim+ CTLs (+3.0%; p=0.03) at 1 day but not 3 months. Interestingly, Ki67+ CTLs increased at day 1 (+0.6%; p<0.001) but decreased by 3 months (-0.6%; p=0.001). There were no significant changes in PD-1+ CTLs at either time point. There were no significant changes in any CTL characteristics at 1 day or 3 months between aggressive and indolent tumors. Conclusions: These findings characterize changing CTL profiles over time with surgical resection of renal tumors which may help guide biomarker development.