Zinc is an essential trace element necessary for over 200 zinc metalloenzymes and required for normal nucleic acid, protein, and membrane metabolism. During the past two decades there has been a rapid expansion of knowledge concerning zinc metabolism in both normal and disease situations, including mechanisms for zinc absorption, excretion and internal redistribution of zinc after stress or trauma. Acrodermatitis enteropathica has been recognized to be a disease of impaired zinc absorption in man. A host of disease processes now are recognized to be complicated by zinc deficiency including alcoholic liver disease, sickle cell anemia, protein calorie malnutrition, and a variety of intestinal diseases including Crohn's disease, sprue, short bowel syndrome and after jejunal ileal bypass. Zinc has proved to be an extremely interesting mineral to nutritionists and physicians because of its importance in normal physiology and biochemistry and because of the diverse presenting features of zinc deficiency. This paper reviews ten functional consequences of zinc deficiency and emphasizes certain consequences in which there have been new discoveries concerning their mechanism (e.g., anorexia) or their clinical importance (e.g., immune dysfunction).