Summary 1. The incidence of ammonia dermatitis has been greatly reduced during the past thirty years because of proper diagnosis of symptoms and the initiation of successful therapeutic measures. 2. Commercial diaper laundries employvarious chemicals for the prevention of ammonia dermatitis. The chemicals commonly used have been either mercurial or quaternary ammonium compounds. 3. Home laundries have had bothtype compounds available but because of cost, toxicity, and difficulty of handling they have not been generally used. 4. O-benzyl-p-chlorophenol (Stero-Test)eliminates these objections in addition to showing greater range of effectivity in hard and soft water. Soaps, anionic detergents, and organic material do not interfere with the bacteriostatic or bactericidal efficiency of Stero-Test.