MicroRNAs (miRNAs) are a group of small, noncoding RNAs that act as novel regulators of gene expression through the post-transcriptional repression of their target mRNAs. miRNAs have been implicated in diverse biologic processes, and it is estimated that up to half of all transcripts are regulated by miRNAs. Recent studies also demonstrate a critical role for miRNAs in renal development, physiology, and pathophysiology. Understanding the function of miRNAs in the kidney may lead to innovative approaches to renal disease.