It is well recognized that zinc is an essential trace element, influencing growth and affecting the development and integrity of the immune system. Research has begun to clarify the molecular mechanisms underlying the action of zinc on the immune function. It is clear that this trace element has a broad impact on key immunity mediators, such as enzymes, thymic peptides and cytokines, explaining the paramount importance of zinc's status on the regulation of lymphoid cell activation, proliferation and apoptosis. Ongoing and future studies regarding the immunological status of zinc deficiency 'at risk' groups could lead to public health interventions with nutritional doses of zinc supplements to prevent alteration of the immune system and improve resistance to infections.