Inadequate nutriture of zinc, copper and iron alter immunocompetence in humans and experimental animals. For each of these minerals deficient status leads to increased susceptibility to infectious illnesses. Specific components of the immune response may be altered in a variety of patients and models. Although many generalized functions for these nutrients could lead to altered immune function, specific functions for these minerals in immunity have not yet been identified. For zinc, copper and iron the importance of adequate nutrition in maintaining immunocompetency cannot be understated.