Chronic kidney diseases are a social and economic problem, and diet has long been recognized as a fundamental modulator of kidney health in human and experimental models. Age-dependent alterations in mitochondrial function play a crucial role in the development of diseases of aging, and mitochondrial disorders have been observed in experimental models of kidney failure. Recently, the beneficial dietary effect of a specific mixture of essential amino acids (EAA) has been studied in elderly subjects, but no data were collected from the kidney. The aim of this study was to assess whether daily supplementation of the diet with EAA at the beginning of senescence could preserve renal health. We used middle-aged (18-month-old) male Wistar rats fed a standard diet and water ad libitum (M-aged group) or a diet with added EAA (1.5 g/kg per day) dissolved in drinking water for 3 months (M-aged+EAA group). Young (2-month-old) rats fed a standard diet for 3 months were used as controls. Mitochondrial morphology and markers for collagen, cyt-c-oxidase, HSP60, GRP75, eNOS, iNOS, Bax, Bcl2 and VEGF were analyzed in glomeruli and tubules. EAA supplementation limited fibrosis and increased the capillary tuft area in the glomeruli of M-aged rats. VEGF and eNOS were enhanced in glomeruli and the peritubular space with the EAA-supplemented diet. Mitochondrial cyt-c oxidase, Bcl2, and chaperones increased in the distal tubules of the EAA group to levels similar to those observed in the young group. Mitochondrial area and density after EAA intake did not differ from young groups. The results suggest that prolonged EAA intake could represent a strategy for maintaining the healthy status of the kidney in M-aged animals.