Kidneys comprise the paired organ essentially responsible for excreting nitrogenous wastes, excessive water, inorganic salts, and toxic substances produced during the process of body metabolism. The maintenance of osmotic regulation and homeostatic fluid balance of the body is also performed by the kidneys. The current study investigated the histological features in quail birds of both genders at different age stages. A total of thirty-six adult male and female Japanese quail were allocated randomly into four different age groups of 30, 90, 180, and 270 days. They were fed high-protein food and water for two weeks, after which the kidneys of the quail were obtained and histological changes between males and females were evaluated. Data analysis was performed using SPSS-22. The results showed a 24% increase in Bowman's space in male quail compared with females after 30 days. Moreover, a 10% increase in Bowman's space was recorded at 270 days in male quail compared with females. The results showed a 12% increase in glomerular diameter in females compared with males. The data also showed a 12% increase in the diameter of Bowman's capsule in females compared to males. The outer diameter of the thin tubule in the loop of Henle in females increased by 4% compared to males. A 12%increase was noted in the outer diameter of the thickened tubule and the collecting tubes in male quail compared to the females at 30 days of age. Increases in the outer diameter of the proximal tubule of 6%, 16%, and 2% in female quail compared to males were recorded at 30, 180, and 270 days, respectively. Finally, the outer diameter of the distal tubule in males increased by 4% compared to females at 30 days and by 2% at 270 days. The current study described in detail the effect of a high-protein diet on the histology of different genders in quail kidney. Copyright © 2021 by Razi Vaccine & Serum Research Institute