Abstract: While the etiology of diaper dermatitis in infants is complex, it is generally believed to involve an interaction between skin and irritants in feces and urine. Proteases and lipases were identified as the major irritants in the feces of infants, and bile salts were found to potentiate the damage produced by the action of fecal enzymes on skin. Fecal enzymes also increased the permeability of skin, thereby increasing potential susceptibility to other irritants in the diaper environment.