Background: The diagnosis of upper tract urothelial carcinoma (UTUC) is frequently obtained via diagnostic ureteroscopy (URS) with biopsy. In a recent meta-analysis of five retrospective series comparing UTUC RNU patients with and without prior diagnostic URS, prior URS was associated with intravesical recurrence of urothelial carcinoma. However, there remains an incomplete understanding of the risks of URS on intravesical recurrence after RNU, and existing studies have not examined the risks of URS without endoscopic biopsy or percutaneous biopsy alone. Here, we query our institutional RNU registry to determine if UTUC diagnostic modality influences post-RNU intravesical recurrence risk. Methods: Years 1995 to 2019 of our institutions RNU registry were queried. Patients with UTUC were divided into four groups: 1) URS with endoscopic biopsy; 2) URS without endoscopic biopsy (visual confirmation alone); 3) percutaneous biopsy without any URS; 4) no URS and no percutaneous biopsy. Exclusion criteria included pure non-urothelial histology, RNU for benign indications, and prior/concomitant cystectomy. The primary outcome was intravesical recurrence of urothelial carcinoma compared across the four groups using Kaplan-Meier log-rank analyses and Cox-proportional hazard modeling (hazard ratio = HR). Results: In a cohort of 878 patients (mean post-RNU follow-up 43 months), 461 (53%) had URS with biopsy, 130 (15%) had URS without biopsy, 229 (26%) had no URS or percutaneous biopsy, and 58 (7%) had percutaneous biopsy alone. The 3-year intravesical recurrence rate was 27%, 22%, 18%, 12% for groups 1-4, respectively. Covariates associated with intravesical recurrence on univariable analysis included age (HR 1.03, p < 0.01), female gender (HR 0.76, p = 0.06), history of bladder cancer (HR 1.39, p = 0.01), current smoker (HR 1.49, p = 0.04), and multifocality (HR 1.34, p = 0.03). After adjusting for these covariates, multivariable analysis found that group 1 (URS with biopsy) was associated with increased intravesical recurrence (HR 1.41, p = 0.03) relative to group 3 (no URS or percutaneous biopsy). Compared to group 1, the hazard ratio for intravesical recurrence was not significantly different for group 2 (HR 1.18, p = 0.45) or group 4 (HR 1.11, p = 0.79). Conclusions: Patients undergoing ureteroscopic biopsy to diagnose UTUC prior to RNU had a higher risk of intravesical recurrence after RNU compared to patients who did not undergo any URS or percutaneous biopsy. This agrees with prior literature and suggests that aggressive ureteroscopic manipulation of UTUC tumors via biopsy may promote shedding of urothelial carcinoma cells capable of seeding the bladder. Our study does support the initiation of a randomized trial to determine if intravesical chemotherapy after ureteroscopic biopsy can reduce intravesical urothelial carcinoma recurrences.