The most important factors for maintaining and promoting health are known to be nutrition, exercise and rest. Although there have been many studies on nutrition and immunity, or exercise and immunity, few studies have concomitantly investigated the effects of both nutrition and exercise on host immune functions. Since aging also has great effects on host immune functions, especially cellular immunity, this review covers the effects of nutrition and exercise not only on host immune functions but also the decrease of cellular immune functions in the aged. Animal models of aging have shown that vitamin E (VE) has an ability to restore cellular immune functions that have deteriorated with aging. Furthermore, VE also plays an important role in T-cell differentiation and maturation in the thymus. It has been demonstrated that a bout of treadmill exercise causes a transient decrease of cellular immune function immediately after exercise, which is thought to be related to changes in plasma prostaglandin E2, Iactate and glutamine concentrations. On the other hand, exercise training has been shown to have beneficial effects, both qualitatively and functionally, on celluiar immunity in the aged. From these results, it should be emphasized that appropriate nutrition and exercise training are beneficial for maintaining and promoting health in the aged.