Parakeratosis is a nutritional deficiency disease of 6- to 16-week-old pigs characterized by lesions of the superficial layers of the epidermis. It results from a zinc deficiency or inadequate absorption of zinc due to an excess of calcium, phytates, or other chelating agents in the diet. Predisposing factors include rapid growth, deficiency of essential fatty acids, or malabsorption due to gastrointestinal disease. Parakeratosis is uncommon in commercial swine unless errors have been made in diet formulation; however, it may occur in backyard pigs. The widespread use of high zinc levels in feed to prevent enteric disease in weaned pigs has further reduced the likelihood of the disease.