Recent evidence suggests that copper exacts an important role in the maintenance of immunocompetence. Copper deficiency results in decreased humoral and cell-mediated, as well as nonspecific immune function. Impairment of immune function may be highly correlated with an increased incidence of infection and higher mortality rates observed in copper-deficient animals. The actual mechanisms by which copper is involved in immune processes are not well defined. This review addresses the copper-immune function interaction and discusses possible immunomodulatory roles for copper.