In kidney proximal tubules of male mice the mitochondria are larger and more electron-lucent, autophagic vacuoles and lysosomes (predominantly myeloid bodies) more numerous and voluminous, and exocytosed intraluminal myeloid bodies more common than in females. Males also have higher kidney activities of mitochondrial cytochrome c oxidase and lysosomal hydrolases, and excrete larger quantities of hydrolases and protein in the urine. Orchiectomy evokes the feminine pattern whereas testosterone administration induces the male pattern. Endogenous testosterone modulates mitochondrial structure and function and enhances the activity of the lysosomal-vacuolar system in proximal tubule cells.