The GERDA classes have the function of updating our knowledge of dermato-allergology. One of the themes tackled this year was the treatment of atopic dermatitis. Apart from consideration of treatment or exception with cortisone, it seemed to be of interest to find the relevance of "old treatments" for atopic dermatitis, either preventive or symptomatic. Preventive treatment made reference to correction of food factors (diet in infants, removal of maternal allergens, supplementation on fatty acids) and of environmental factors especially the fight against house dust mites by use of anti-mite mattress covers. Miracle treatments of atopy do not always exist. Thus there is often need for, besides local corticosteroid therapy, an external symptomatic treatment where the emphasis is on the struggle against skin microbiology, the fight against pruritic inflammatory conditions and above all the battle against xerosis. Knowledge of the physiology of the stratum corneum gives better understanding of the effect of emollients and moisturizers in restoration of the cutaneous barrier, of which dysfunction is one of the elements of atopic dermatitis.