Acrodermatitis enteropathica is a rare autosomal recessive disorder characterized by alopecia, acral and periorificial dermatitis and diarrhea. True acrodermatits enteropathica requires lifelong zinc replacement whereas transient acrodermatitis enteropathica, an acquired disorder with identical clinical features, requires only transient zinc replacement. Although premature and milk-fed infants are particularly vulnerable to development of both conditions, there have been some reports of acrodermatitis enteropathica in full-term breast-fed infants. We report a case of transient acrodermatitis enteropathica in a S-month-old, full-term, breast-fed male baby with identical history in his 2 elder siblings. The patient presented with a 5-month history of diarrhea, hair loss and crusted erythematous patches on periorificial areas, and fingers and toes. His serum zinc levels were within lower normal limits in 2 consecutive tests. His mother was also checked for zinc levels, which was normal in serum but was markedly reduced in breast milk. Diarrhea and skin lesions disappeared promptly with oral zinc supplementation and did not recur after 11 weeks of treatment. (Korean J Dermatol 2001;39(10): 1123-1126)