During the recent resurgence of interest in the clinical uses of vitamin E, one of the major foci of attention has been the neurologic role of vitamin E in humans. Studies in patients with secondary vitamin E deficiency, caused by fat malabsorption disorders and total parenteral nutrition lacking an adequate supply of vitamin E, have elucidated a clinical disorder and histologic lesions of the nervous system and muscle that closely resemble those of experimental vitamin-E-deficient animal models. Investigations of the primary form of human vitamin E deficiency, the isolated vitamin E deficiency syndrome, have further substantiated the relationship between neurologic dysfunction and human vitamin E deficiency. It is now clear that vitamin E is an essential nutrient necessary for the optimal development and maintenance of the integrity and function of the human nervous system and skeletal muscle. The task for future study is to determine the mechanism by which vitamin E deficiency causes degeneration of selective regions of the nervous system and to investigate possible benefits of vitamin E supplementation in other neurologic disorders. In addition, further study of the isolated vitamin E deficiency syndrome promises to teach us more about normal physiologic mechanisms of vitamin E absorption and transport in humans.