Several nutrients are known to act on the metabolism of other nutrients and also of some non-nutrient substances. The nutritional importance that may be attributed to these interrelationships depends on the levels considered to be physiological for each nutrient, and on their maintenance at acceptable levels in tissues for the defense of the organism. Interaction of vitamins and minerals has been described in several metabolic situations and continues to be investigated by many authors. This interaction occurs in different ways, i.e. starting from the action of vitamins on mineral metabolism, from the action of both types of nutrients in the protection of the organism, and from the action of minerals on vitamin metabolism. The most significant example of vitamin action on mineral metabolism is the role played by vitamin D in calcium and phosphorus metabolism. The interrelationship of vitamin C and some minerals is also discussed, with emphasis on its relationship with iron. With respect to the synergistic action of vitamins and minerals in the defense of the organism, we comment on the main data reported on the biochemical-physiological role of vitamin E and its interaction with selenium. Finally, in reference to the action of minerals on vitamin metabolism, we point out the interaction existing between vitamin A and zinc. Data observed by the author at the experimental level in laboratory animals are reported on the possible interaction of niacin, vitamin B6 and zinc.