A number of structural changes occur in the kidney with aging. The aging kidney is characterized by loss of renal mass, arterial sclerosis, arteriolar hyalinosis, an increased number of sclerotic glomeruli, loss of tubules and interstitial fibrosis. The pathogenesis of aging-associated structural changes is not completely understood. Both genetic background and hemodynamic factors have been associated with progression of age-related morphological changes. The structural changes of aging kidney are nonspecific and can be seen in many conditions, including diabetes and hypertension, and, as such, arterionephrosclerosis of aging is a diagnosis of exclusion.