During the spring breeding season of the American chameleon, Anolis carolinensis, elevated levels of glucosylceramides which contain hydroxy fatty acids are produced in the kidneys of males but not females. Hyperproduction of this glycolipid is also induced by testosterone. The testosterone-induced hypertrophy of epithelial cells in the proximal tubules of the mouse kidney seems an analogous phenomenon and an elevated concentration of specific glycolipids in the male mouse kidney has been previously demonstrated. Thus the formation of renal glycolipids in response to testosterone may be a widespread feature in vertebrates.