Atopic diseases represent the most prevalent chronic illness in childhood, affecting between 15-30 % of all children in Western countries (4th problem of public health for WOH). Their incidence increased dramatically during the past 30 years. The observed increase in atopic disorders was supposed to be a consequence of changes in lifestyle factors, including improvement in public health, reduction of childhood infection, vaccination programs and changes in family size and living conditions: these factors all reflect reduced microbial burden due to increased hygiene. Food allergy and anaphylaxis in the child are also becoming main manifestations of atopy in infancy and early childhood. Five allergens are responsible for about 85 % of all cases, that can be frequently life-threatening. Diagnosis, treatment and prevention of the disease are analysed. Research on induction of tolerance and prevention were also discussed.