An 11-month-old boy was brought to our clinic with superinfected, sharplydefined, symmetrical, erythematous macules and vesicles, some with yellowish-brownish crusts, on the cheeks, fingers, and in the diaper region. The suspected impetigo contagiosa had failed to respond to both topical antiseptic therapy and systemic antibiotics. Because of the unusual clinical picture and course, we measured the serum zinc level. A significantly reduced level of 2 μmol/l (normal range 9.2–18.4 μmol/l) was identified. Initial skin lesions had appeared one week after weaning (5th week after birth). Since the age of 8 months the infant had also had recurrent diarrhea. Two weeks after zinc-histidine substitution, the diarrhea ceased and skin lesions slowly disappeared. Molecular genetic testing for the SLC39A4 (zinc transporter) gene revealed compound heterozygosity for the previously unidentified mutations c.1465_1474+4del (p.) and c.295G>A (p.Ala99Thr). The parents are healthy heterozygous gene carriers. The same compound heterozygosity was later detected in the newborn brother of our patient shortly after birth. A zinc deficiency could therefore be identified and treated before symptoms occurred. The inherited autosomal recessive zinc transporter deficiency is termed acrodermatitis enteropathica. Lifelong zinc substitution is recommended. A differential diagnosis can be difficult because bacterial and fungal superinfection is common in zinc deficiency. Precise diagnosis requires testing family members for the gene.