Purpose of reviewNotch signaling is a highly conserved mechanism used by multicellular animals to specify cell fate decisions during the formation of complex structures such as the kidney. A number of studies have recently identified requirements for Notch signaling during kidney organogenesis and tissue repair. This review will summarize these studies and compare Notch signaling in the mammalian kidney with Notch signaling in other organ systems.Recent findingsA targeted mutation in the mouseNotch2receptor resulted in kidneys that are devoid of glomerular endothelial and mesangial cells. The mutant epithelial cells of the developing glomerulus have reduced amounts of vascular endothelial growth factor expression, which may be responsible for the lack of vascularization observed in these glomeruli.Notch2is expressed in the epithelial cells of the developing glomerulus, and a potential ligand,Jagged1, is expressed in the endothelial cells of the glomerulus. Mice simultaneously heterozygous for mutations in bothNotch2andJagged1phenocopy the kidney defects seen in mice homozygous for theNotch2mutation. These doubly heterozygous mice also display liver and heart developmental abnormalities reminiscent of Alagille's syndrome.SummaryNotch signaling is required for kidney development, and the expression of Notch genes is increased in response to kidney damage. Further studies of Notch signaling will be important in order to understand kidney development and tissue repair.