Zinc deficiency occurs as a genetic disorder, acrodermatitis enteropathica, or as an acquired disorder resulting from inadequate intake or malabsorption of zinc. It is now apparent that human breast milk may not always protect against the development of clinical zinc deficiency in premature and in full-term infants. In the absence of other predisposing factors, low levels of zinc in breast milk may precipitate zinc deficiency in breast-fed infants. This report confirms that breast-fed full-term infants may develop a clinical picture indistinguishable from acrodermatitis enteropathica.