Background: The CARMENA study found no survival benefit from cytoreductive nephrectomy (CN) in poor-risk metastatic renal cell cancer (mRCC) patients treated with first line Sunitinib. Although retrospective studies have reported survival benefits with CN following immunotherapy (IO)-based therapy, the timing remains unclear. We aimed to investigate the ideal timing of CN following IO using the National Cancer Database. Methods: 783 patients with de novo mRCC were diagnosed between 2016 and 2020 who received upfront systemic therapy and underwent CN, 343 patients met our criteria. Patients were categorized into four groups based on the timing of nephrectomy: CN ≤3 months (Group A), 4 to 6 months (Group B), 7 to 9 months (Group C) and ≥ 10 months (Group D) following the initiation of IO-based therapy. Descriptive analysis was performed to examine the demographic and clinical characteristics. Follow up time was measured from the date of surgery to reduce bias. Kaplan-Meier plots were used to analyze survival curves, and a multivariable cox regression analysis was performed to explore associations between timing and survival. Results: 343 patients who received upfront IO -based therapy were divided into four groups: 104 (30%) in A, 114 (33%) in B, 74 (22%) in C and 51 (15%) in D. 71%were male, white (90%), age 40 – 64 (62%), comorbidity index 0 (70%), clear cell histology (69%), sarcomatoid (14%). 54% were treated in academia, 57% had bone metastasis, 50% had lung, 11% had liver, and 7% had brain metastases. 66% received only IO, and 34% received IO + TKI. No significant association between CN timing and survival observed in multivariate cox regression model. (HR 0.87, 95% CI: 0.5- 1.7, p = 0.84). Compared to group A, the HR were 0.96 (95% CI, 0.73 to 1.27; p=0.78), 0.77 (95% CI, 0.53 to 1.13; p=0.19), and 0.66 (95% CI, 0.37 to 1.20; p=0.17) respectively for groups B, C and D. Conclusions: Our study did not find significant survival improvement with an optimal timing of CN following IO-based therapy, while HRs were reduced after 6 months of delay, though insignificant. This could be due to the small sample size or other confounders.