Zinc concentration was determined in epidermis, papillary dermis and serum in patients with dermatitis herpetiformis, acne or psoriasis and in two small groups of patients with ichthyosis vulgaris and Darier's disease. Except in ichthyosis vulgaris the zinc level in epidermis was decreased in all these disorders. The mean serum zinc concentration was, however, significantly decreased only in men with dermatitis herpetiformis. There was no correlation between the concentration of zinc in epidermis or dermis and that in serum. The decreased epidermal zinc concentration indicates that many of the patients have a zinc deficiency in spite of a "normal" serum zinc value. Supplementation of zinc might therefore be of value in patients with these disorders.