Iron is an essential element for all living organisms, but produces toxic oxidants. Thus, iron homeostasis is tightly regulated in mammals. Hepcidin-25 (hepcidin) has emerged as a molecule that regulates iron metabolism. Binding of hepcidin to its receptor, ferroportin, inhibits intestinal iron absorption and iron efflux from hepatocytes and macrophages. Decreased hepcidin enhances iron absorption and efflux. Hepcidin could be predictive of iron status and the response to iron supplementation or erythropoietin-stimulating agents. Monitoring hepcidin is helpful for the management of anemia. Thus, it is urgent to obtain normal reference values in a large population of healthy subjects and to standardize various hepcidin assays, which enables to compare the data measured by different methods. Anemia is an important and common problem associated with chronic kidney disease (CKD), which is caused by erythropoietin deficiency, iron-restricted erythropoiesis, inflammation, hypoxia, vitamin D deficiency, hyperparathyroidism, and obesity. Anemia causes poor quality of life, progression of CKD, increased risk of cardiovascular events, and mortality. Besides its role in anemia, recent evidence suggests that hepcidin-25 plays a role in the pathogenesis and progression of kidney injury via modulation of iron-mediated oxidant injury. Despite accumulating experimental data, information about clinical significance of hepcidin-25 for anemia and kidney injury in CKD patients is scarce, especially in children. This review summarizes the current knowledge of the role of hepcidin-25 in the regulation of anemia and kidney injury in children and adults with CKD. Strategy for modulating hepcidin-25 to prevent anemia and kidney injury associated with CKD is also discussed.