PURPOSE: Urothelial carcinoma has a higher incidence in renal transplanted patients according to several registries (relative risk × 3), and the global prognosis is inferior to the general population. The potential impact of immunosuppressive therapy on the feasibility, efficacy, and complications of endovesical treatment, especially Bacillus Calmette-Guerin, has a low level of evidence. We performed a systematic review that aimed to assess the morbidity and oncological outcomes of adjuvant endovesical treatment in solid organ transplanted patients. METHODS: Medline was searched up to December 2021 for all relevant publications reporting oncologic outcomes of endovesical treatment in solid organ transplanted patients with NMIBC. Data were synthesized in light of methodological and clinical heterogeneity. RESULTS: Twenty-three retrospective studies enrolling 238 patients were included: 206 (96%) kidney transplants, 5 (2%) liver transplants, and 2 (1%) heart transplants. Concerning staging: 25% were pTa, 62% were pT1, and 22% were CIS. 140/238 (59%) patients did not receive adjuvant treatment, 50/238 (21%) received mitomycin C, 4/238 (2%) received epirubicin, and 46/238 (19%) received BCG. Disease-free survival reached 35% with TURBT only vs. 47% with endovesical treatment (Chi-square test p = 0.08 OR 1.2 [0.98-1.53]). The complication rate of endovesical treatment was 12% and was all minor (Clavien-Dindo I). CONCLUSION: In solid organ transplanted patients under immunosuppressive treatment, both endovesical chemotherapy and BCG are safe, but the level of evidence concerning efficacy in comparison with the general population is low. According to these results, adjuvant treatment should be proposed for NMIC in transplanted patients as in the general population.