Abstract: MicroRNA (miRNA) markers are important in the diagnosis, monitoring, and prognosis of tumors. Urine samples can be collected conveniently and non-invasively. Thus, urinary miRNA present in urine samples has attracted increasing attention as a tumor marker. A variety of urinary miRNAs have been linked to the diagnosis of tumors. This review discusses the function and detection methods of miRNAs, and the importance of urinary miRNAs in urinary and non-urinary system tumors. The information may aid in further clinical diagnosis, monitoring, and prognosis of tumors.