MicroRNAs (miRNAs) are short non-coding RNAs regulating gene expression at the post-transcriptional level by blocking translation or promoting cleavage of their target mRNAs. Increasing evidence shows that miRNAs play central roles in gene transcription, signal transduction and pathogenesis of human diseases. Diabetic nephropathy (DN) is a severe microvascular complication that can lead to end-stage renal disease. Increased expansion (hypertrophy) and accumulation of extracellular matrix (ECM) proteins such as collagen (fibrosis) in the glomerular mesangium along with glomerular podocyte dysfunction are major features of DN. Profiling of miRNAs and study\ of their functions in renal glomeruli can provide critical new information to advance our knowledge of DN as well as other kidney diseases and thereby uncover much needed new therapeutic targets. In this review, we summarize the biogenesis of miRNAs and their functions in the glomerulus, with particular emphasis on glomerular mesangial cells and podocytes related to the pathogenesis of DN.