Three patients with acrodermatitis enteropathica (AE), a disorder of Zn metabolism, demonstrated a Zn-responsive defect in chemotaxis of neutrophils and monocytes. Monocyte chemotaxis was depressed during a controlled period of Zn deficiency and increased to normal values after administration of oral zinc sulfate supplements that was sufficient to restore normal plasma Zn levels. In the only patient in whom neutrophils were also studied, a similar defect in chemotaxis of neutrophils was corrected by administration of zinc sulfate supplements. Preincubation of defective cells in vitro with zinc sulfate increased chemotaxis in an almost linear dose-response relationship. Zn is apparently important in neutrophil and monocyte chemotaxis and demonstrate a correctable immune defect in AE.