Toll-like receptors (TLRs) recognize both exogenous microbial components and endogenous molecules to promote immune activation. Both immune and nonimmune renal cells express TLRs, which are involved in the pathogenesis of a number of kidney diseases, including pyelonephritis, Leptospira nephritis, immune-complex glomerulonephritis, ischemic/reperfusion injury, and rejection of kidney transplant.