Recently, our understanding of podocytes has been greatly advanced by genetic analysis of human kidney diseases and corresponding animal models, establishment of podocyte cell lines, and discovery of podocyte specific promoters that facilitate transgenic research. Accumulating data indicate that podocyte injury initiates the process of the disease progression to glomerular sclerosis, a hallmark of chronic renal failure. In the progression to glomerular sclerosis, damages that initially affect only podocytes propagate to mesangial cells, glomerular endothelial cells and parietal epithelial cells. However, the mechanism underlying the propagation of injury from podocytes to other glomerular cells is largely unknown. Several recent topics regarding the mechanism of podocyte injury are also discussed.