The aging process results in remarkable changes in the kidney. These changes are both anatomical and functional and have been considered the cause of the increased propensity of the elderly to acute or chronic renal failure. However, the majority of the early studies on aging enrolled institutionalized elderly patients with several comorbidities such as hypertension and heart disease which could by themselves induce renal alterations. Recently the selection of subjects lacking renal disease or processes known to affect renal function has demonstrated that aging changes are less pronounced in healthy aged subjects. Nonetheless, understanding aging-induced renal changes may help to prevent life-threatening kidney disease. This review will focus on glomerular hemodynamics, and on renal sodium and potassium handling and diluting and concentrating ability.