Aging is a complex biological process, with gradual and progressive decline in structure and function in many organ systems. Our objective is to determine if structural changes produced by aging, vary with sex, in a stressful situation such as dehydration. The expression of Slc12a3 mRNA in renal cortex, α-smooth muscle actin (α-SMA) and fibronectin, was evaluated in male and female rats aged 3 and 18 months submitted or not to water deprivation (WD) for 48 hours. When comparing ages, 18-month-old males showed lower expression of Slc12a3 mRNA than 3-month-old males, and control and WD 18-moth-old male and female rats exhibited higher expression of α-SMA than respective 3-month-old rats. Fibronectin was higher in both control and WD 18-month-old males than respective 3-month-old males. In females, only control 18-month-old rats showed higher fibronectin than control 3-month-old rats. When we compared sex, control and WD 3-month-old female rats had lower expression of Slc12a3 mRNA than re-spective males. WD 18-month-old male rats presented higher expression of fibronectin and α-SMA than WD 18-month-old female rats. When we compared hydric condition, WD 18-month-old males displayed lower relative expression of Slc12a3 mRNA and higher α-SMA expression than control 18-month-old males. Aging, sex, and dehydration lead to alteration in kidney structure.