Background: Upper tract urothelial carcinoma (UTUC) is histologically similar to bladder urothelial carcinoma (BUC), yet several clinical, biological and molecular features are unique to UTUC. UTUC may have unique genomic factors compared to BUC, while major knowledge gaps remain in our understanding of the biology and genomic landscape of UTUC. Methods: We retrospectively sequenced tumor samples and matched germline DNA using targeted next-generation sequencing methods and analyzed at least 642 cancer-associated genes. The cohort included 35 UTUC patients and 36 BUC patients. Results: Among all cases, KMT2D and TP53 were the most common mutations (account for 66% and 75% in UTUC and BUC, respectively). The most frequently mutated genes in UTUC were KMT2D (37%), TP53 (29%), ELF3 (26%), FGFR3 (23%), ASXL1 (20%), DKN2A (20%), DKN2B (17%), REBBP (17%), MT3B (17%), GNAS (17%) and PIK3CA (17%). The most frequently mutated genes in BUC were KMT2D (36%), TP53 (39%), MUC17 (14%), ARID1A (22%), GNAS (19%), RB1 (19%), BCL6 (19%), E2F3 (19%), EIF4A2 (19%) and FGF3 (19%). However significant differences in the prevalence of mutations in individual genes were observed. FGFR3 (23% vs. 8%) and ELF3 (26% vs. 11%) were more frequently altered, whereas RB1 (6% vs. 19%), E2F3 (3% vs. 19%) and BCL6 (3% vs. 19%) were less frequently altered in UTUC (P < 0.05). FGFR3 mutations have been shown to be oncogenic and RB1 inactivation has been associated with genomic instability in urothelial cancer in previous researches, which represent potential therapeutic targets. Conclusions:Â UTUC and UCB exhibit significant differences in the prevalence of genomic landscape and carcinogenesis. A comprehensive understanding of the biology of UTUC and UCB is needed to identify new drug targets in order to improve clinical outcomes.