Proteins and small molecules in urine (biomarkers) have been used to probe for kidney and systemic diseases for hundreds of years. Urine reportedly contains a type of molecule called microRNA (miRNAs) that regulate a large number of biological processes. Impaired function of miRNAs is now recognized in an increasing number of disease processes. In the search for new biomarkers, the regulatory function of miRNAs and the relative simplicity and precision of characterizing miRNAs, are potential advantages when compared to traditional biomarkers.