The adrenal cortex of male Sprague-Dawley weanling rats maintained on a zinc-deficient diet was studied by electron microscopy. There was a gradual increase in lipid droplets in the zona fasciculata which was quite marked at 7 weeks, but increased lipid was not observed in the zona glomerulosa or reticularis of zinc-deficient rats. The adrenal cortex of the control animals did not show altered lipid content. A possible explanation for the effect of zinc deficiency on the adrenal cortex is offered.Address reprint requests to A.E. Leure-duPree, Ph. D.,